COVID-19 vaccine

From Wikipedia the free encyclopedia

Share of people who received at least one dose of COVID-19 vaccine
Map of countries by approval status
  Approved for general use, mass vaccination underway
  EUA (or equivalent) granted, mass vaccination underway
  EUA granted, limited vaccination
  Approved for general use, mass vaccination planned
  EUA granted, mass vaccination planned
  EUA pending
  No data available

A COVID‑19 vaccine is a vaccine intended to provide acquired immunity against severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2), the virus causing coronavirus disease 2019 (COVID‑19). Prior to the COVID‑19 pandemic, an established body of knowledge existed about the structure and function of coronaviruses causing diseases like severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). This knowledge accelerated the development of various vaccine technologies during early 2020.[1] On 10 January 2020, the SARS-CoV-2 genetic sequence data was shared through GISAID, and by 19 March, the global pharmaceutical industry announced a major commitment to address COVID-19.[2]

In Phase III trials, several COVID‑19 vaccines have demonstrated efficacy as high as 95% in preventing symptomatic COVID‑19 infections. As of April 2021, 17 vaccines are authorized by at least one national regulatory authority for public use: two RNA vaccines (Pfizer–BioNTech and Moderna), eight conventional inactivated vaccines (BBIBP-CorV, CoronaVac, Covaxin, CoviVac, COVIran Barakat, Minhai-Kangtai and QazVac, WIBP-CorV), five viral vector vaccines (Sputnik Light, Sputnik V, Oxford–AstraZeneca, Convidecia, and Johnson & Johnson), and two protein subunit vaccines (EpiVacCorona and RBD-Dimer).[3][failed verification] In total, as of March 2021, 308 vaccine candidates are in various stages of development, with 73 in clinical research, including 24 in Phase I trials, 33 in Phase I–II trials, and 16 in Phase III development.[3]

Many countries have implemented phased distribution plans that prioritize those at highest risk of complications, such as the elderly, and those at high risk of exposure and transmission, such as healthcare workers.[4] Single dose interim use is under consideration in order to extend vaccination to as many people as possible until vaccine availability improves.[5][6][7][8]

As of 6 June 2021, 2.15 billion doses of COVID‑19 vaccine have been administered worldwide based on official reports from national health agencies.[9] AstraZeneca anticipates producing 3 billion doses in 2021, Pfizer–BioNTech 1.3 billion doses, and Sputnik V, Sinopharm, Sinovac, and Johnson & Johnson 1 billion doses each. Moderna targets producing 600 million doses and Convidecia 500 million doses in 2021.[10][11] By December 2020, more than 10 billion vaccine doses had been preordered by countries,[12] with about half of the doses purchased by high-income countries comprising 14% of the world's population.[13]


A CDC Fact sheet about COVID-19 vaccines
A US airman receiving a COVID-19 vaccine

Prior to COVID‑19, a vaccine for an infectious disease had never been produced in less than several years – and no vaccine existed for preventing a coronavirus infection in humans.[14] However, vaccines have been produced against several animal diseases caused by coronaviruses, including (as of 2003) infectious bronchitis virus in birds, canine coronavirus, and feline coronavirus.[15] Previous projects to develop vaccines for viruses in the family Coronaviridae that affect humans have been aimed at severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). Vaccines against SARS[16] and MERS[17] have been tested in non-human animals.

According to studies published in 2005 and 2006, the identification and development of novel vaccines and medicines to treat SARS was a priority for governments and public health agencies around the world at that time.[18][19][20] As of 2020, there is no cure or protective vaccine proven to be safe and effective against SARS in humans.[21][22] There is also no proven vaccine against MERS.[23] When MERS became prevalent, it was believed that existing SARS research might provide a useful template for developing vaccines and therapeutics against a MERS-CoV infection.[21][24] As of March 2020, there was one (DNA-based) MERS vaccine which completed Phase I clinical trials in humans,[25] and three others in progress, all being viral-vectored vaccines: two adenoviral-vectored (ChAdOx1-MERS, BVRS-GamVac) and one MVA-vectored (MVA-MERS-S).[26]

Planning and development

Since January 2020, vaccine development has been expedited via unprecedented collaboration in the multinational pharmaceutical industry and between governments.[27]

Multiple steps along the entire development path are evaluated, including:[14][28]

  • the level of acceptable toxicity of the vaccine (its safety),
  • targeting vulnerable populations,
  • the need for vaccine efficacy breakthroughs,
  • the duration of vaccination protection,
  • special delivery systems (such as oral or nasal, rather than by injection),
  • dose regimen,
  • stability and storage characteristics,
  • emergency use authorization before formal licensing,
  • optimal manufacturing for scaling to billions of doses, and
  • dissemination of the licensed vaccine.


There have been several unique challenges with COVID-19 vaccine development.

The urgency to create a vaccine for COVID‑19 led to compressed schedules that shortened the standard vaccine development timeline, in some cases combining clinical trial steps over months, a process typically conducted sequentially over years.[29]

Timelines for conducting clinical research – normally a sequential process requiring years – are being compressed into safety, efficacy, and dosing trials running simultaneously over months, potentially compromising safety assurance.[29][30] As an example, Chinese vaccine developers and the government Chinese Center for Disease Control and Prevention began their efforts in January 2020,[31] and by March were pursuing numerous candidates on short timelines, with the goal to showcase Chinese technology strengths over those of the United States, and to reassure the Chinese people about the quality of vaccines produced in China.[29][32]

The rapid development and urgency of producing a vaccine for the COVID‑19 pandemic may increase the risks and failure rate of delivering a safe, effective vaccine.[33][34][35] Additionally, research at universities is obstructed by physical distancing and closing of laboratories.[36][37]

Vaccines must progress through several phases of clinical trials to test for safety, immunogenicity, effectiveness, dose levels and adverse effects of the candidate vaccine.[38][39] Vaccine developers have to invest resources internationally to find enough participants for Phase II–III clinical trials when the virus has proved to be a "moving target" of changing transmission rates across and within countries, forcing companies to compete for trial participants.[40] Clinical trial organizers also may encounter people unwilling to be vaccinated due to vaccine hesitancy[41] or disbelief in the science of the vaccine technology and its ability to prevent infection.[42] As new vaccines are developed during the COVID‑19 pandemic, licensure of COVID‑19 vaccine candidates requires submission of a full dossier of information on development and manufacturing quality.[43][44][45]


Internationally, the Access to COVID-19 Tools Accelerator is a G20 and World Health Organization (WHO) initiative announced in April 2020.[46][47] It is a cross-discipline support structure to enable partners to share resources and knowledge. It comprises four pillars, each managed by two to three collaborating partners: Vaccines (also called "COVAX"), Diagnostics, Therapeutics, and Health Systems Connector.[48] The WHO's April 2020 "R&D Blueprint (for the) novel Coronavirus" documented a "large, international, multi-site, individually randomized controlled clinical trial" to allow "the concurrent evaluation of the benefits and risks of each promising candidate vaccine within 3–6 months of it being made available for the trial." The WHO vaccine coalition will prioritize which vaccines should go into Phase II and III clinical trials, and determine harmonized Phase III protocols for all vaccines achieving the pivotal trial stage.[49]

National governments have also been involved in vaccine development. Canada announced funding for 96 research vaccine research projects at Canadian companies and universities, with plans to establish a "vaccine bank" that could be used if another coronavirus outbreak occurs,[50] and to support clinical trials and develop manufacturing and supply chains for vaccines.[51]

China provided low-rate loans to one vaccine developer through its central bank, and "quickly made land available for the company" to build production plants.[30] Three Chinese vaccine companies and research institutes are supported by the government for financing research, conducting clinical trials, and manufacturing.[52]

Great Britain formed a COVID‑19 vaccine task force in April 2020 to stimulate local efforts for accelerated development of a vaccine through collaborations of industry, universities, and government agencies. It encompassed every phase of development from research to manufacturing.[53]

In the United States, the Biomedical Advanced Research and Development Authority (BARDA), a federal agency funding disease-fighting technology, announced investments to support American COVID‑19 vaccine development, and manufacture of the most promising candidates.[30][54] In May 2020, the government announced funding for a fast-track program called Operation Warp Speed.[55][56]

Large pharmaceutical companies with experience in making vaccines at scale, including Johnson & Johnson, AstraZeneca, and GlaxoSmithKline (GSK), formed alliances with biotechnology companies, governments, and universities to accelerate progression towards effective vaccines.[30][29]


COVID‑19 vaccine research samples in a NIAID lab freezer (30 January 2020)

COVID-19's causative virus, SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), was isolated in late 2019.[57] Its genetic sequence was published on 11 January 2020, triggering an urgent international response to prepare for an outbreak and hasten development of a preventive COVID-19 vaccine.[58][59][60] Since early 2020, vaccine development has been expedited via unprecedented collaboration in the multinational pharmaceutical industry and between governments.[61] By June 2020, tens of billions of dollars were invested by corporations, governments, international health organizations, and university research groups to develop dozens of vaccine candidates and prepare for global vaccination programs to immunize against COVID‑19 infection.[59][62][63][64] According to the Coalition for Epidemic Preparedness Innovations (CEPI), the geographic distribution of COVID‑19 vaccine development shows North American entities to have about 40% of the activity, compared to 30% in Asia and Australia, 26% in Europe, and a few projects in South America and Africa.[58][61]

In February 2020, the WHO said it did not expect a vaccine against SARS‑CoV‑2 to become available in less than 18 months.[65] The rapidly growing infection rate of COVID‑19 worldwide during early 2020 stimulated international alliances and government efforts to urgently organize resources to make multiple vaccines on shortened timelines,[66] with four vaccine candidates entering human evaluation in March (see COVID-19 vaccine § Trial and authorization status).[58][67]

On 24 June 2020, China approved the CanSino vaccine for limited use in the military, and two inactivated virus vaccines for emergency use in high-risk occupations.[68] On 11 August 2020, Russia announced the approval of its Sputnik V vaccine for emergency use, though one month later only small amounts of the vaccine had been distributed for use outside of the phase 3 trial.[69]

The Pfizer–BioNTech partnership submitted an EUA request to the FDA for the mRNA vaccine BNT162b2 (active ingredient tozinameran) on 20 November 2020.[70][71] On 2 December 2020, the United Kingdom's Medicines and Healthcare products Regulatory Agency (MHRA) gave temporary regulatory approval for the Pfizer–BioNTech vaccine,[72][73] becoming the first country to approve this vaccine and the first country in the Western world to approve the use of any COVID‑19 vaccine.[74][75][76] As of 21 December, many countries and the European Union[77] had authorized or approved the Pfizer–BioNTech COVID‑19 vaccine. Bahrain and the United Arab Emirates granted emergency marketing authorization for BBIBP-CorV, manufactured by Sinopharm.[78][79] On 11 December 2020, the United States Food and Drug Administration (FDA) granted an Emergency Use Authorization (EUA) for the Pfizer–BioNTech COVID‑19 vaccine.[80] A week later, they granted an EUA for mRNA-1273, the Moderna vaccine.[81][82][83][84]

On March 31, 2021, the Russian government announced that they had registered the first COVID-19 vaccine for animals.[85] Named Carnivac-Cov, it is an inactivated vaccine for carnivorous animals, including pets, aimed at preventing mutations that occur during the interspecies transmission of SARS-CoV-2.[86]

In June 2021, a report revealed that the UB-612 vaccine, developed by the US-based COVAXX, was a venture initiated for profits by the Blackwater founder Erik Prince. In a series of text messages to Paul Behrends, the close associate recruited for the COVAXX project, Prince described the profit-making possibilities in selling the Covid-19 vaccines. COVAXX provided no data from the clinical trials on safety or efficacy. The responsibility of creating distribution networks was assigned to an Abu Dhabi-based entity, which was mentioned as “Windward Capital” on the COVAXX letterhead but was actually Windward Holdings. The sole shareholder of the firm, which handled "professional, scientific and technical activities", was Erik Prince. In March 2021, COVAXX raised $1.35 billion in a private placement.[87]

Vaccine types

Conceptual diagram showing three vaccine types for forming SARS‑CoV‑2 proteins to prompt an immune response: (1) RNA vaccine, (2) subunit vaccine, (3) viral vector vaccine
Vaccine platforms being employed for SARS-CoV-2. Whole virus vaccines include both attenuated and inactivated forms of the virus. Protein and peptide subunit vaccines are usually combined with an adjuvant in order to enhance immunogenicity. The main emphasis in SARS-CoV-2 vaccine development has been on using the whole spike protein in its trimeric form, or components of it, such as the RBD region. Multiple non-replicating viral vector vaccines have been developed, particularly focused on adenovirus, while there has been less emphasis on the replicating viral vector constructs.[88]

As of January 2021, nine different technology platforms – with the technology of numerous candidates remaining undefined[clarification needed] – are under research and development to create an effective vaccine against COVID‑19.[3][27] Most of the platforms of vaccine candidates in clinical trials are focused on the coronavirus spike protein and its variants as the primary antigen of COVID‑19 infection.[27] Platforms being developed in 2020 involved nucleic acid technologies (nucleoside-modified messenger RNA and DNA), non-replicating viral vectors, peptides, recombinant proteins, live attenuated viruses, and inactivated viruses.[14][27][33][34]

Many vaccine technologies being developed for COVID‑19 are not like vaccines already in use to prevent influenza, but rather are using "next-generation" strategies for precise targeting of COVID‑19 infection mechanisms.[27][33][34] Several of the synthetic vaccines use a 2P mutation to lock the spike protein into its prefusion configuration, stimulating an immune response to the virus before it attaches to a human cell.[89] Vaccine platforms in development may improve flexibility for antigen manipulation, and effectiveness for targeting mechanisms of COVID‑19 infection in susceptible population subgroups, such as healthcare workers, the elderly, children, pregnant women, and people with weakened immune systems.[27][33]

RNA vaccines

Diagram of the operation of an RNA vaccine. Messenger RNA contained in the vaccine enters cells and is translated into foreign proteins, which trigger an immune response.

An RNA vaccine contains RNA which, when introduced into a tissue, acts as messenger RNA (mRNA) to cause the cells to build the foreign protein and stimulate an adaptive immune response which teaches the body how to identify and destroy the corresponding pathogen or cancer cells. RNA vaccines often, but not always, use nucleoside-modified messenger RNA. The delivery of mRNA is achieved by a coformulation of the molecule into lipid nanoparticles which protect the RNA strands and help their absorption into the cells.[90][91][92][93]

RNA vaccines were the first COVID-19 vaccines to be authorized in the United Kingdom, the United States and the European Union.[94][95] As of January 2021, authorized vaccines of this type are the Pfizer–BioNTech COVID-19 vaccine[96][97][98] and the Moderna COVID-19 vaccine.[99][100] As of February 2021, the CVnCoV RNA vaccine from CureVac is awaiting authorization in the EU.[101]

Severe allergic reactions are rare. In December 2020, 1,893,360 first doses of Pfizer–BioNTech COVID‑19 vaccine administration resulted in 175 cases of severe allergic reaction, of which 21 were anaphylaxis.[102] For 4,041,396 Moderna COVID-19 vaccine dose administrations in December 2020 and January 2021, only ten cases of anaphylaxis were reported.[102] The lipid nanoparticles were most likely responsible for the allergic reactions.[102]

Adenovirus vector vaccines

These vaccines are examples of non-replicating viral vector vaccines, using an adenovirus shell containing DNA that encodes a SARS‑CoV‑2 protein.[103][104] The viral vector-based vaccines against COVID-19 are non-replicating, meaning that they do not make new virus particles, but rather produce only the antigen which elicits a systemic immune response.[103]

As of January 2021, authorized vaccines of this type are the Oxford–AstraZeneca COVID-19 vaccine,[105][106][107] the Sputnik V COVID-19 vaccine,[108] Convidecia, and the Johnson & Johnson COVID-19 vaccine.[109][110]

Convidecia and the Johnson & Johnson COVID-19 vaccine are both one-shot vaccines which offer less complicated logistics and can be stored under ordinary refrigeration for several months.[111][112]

The Sputnik V COVID-19 vaccine uses Ad26 for the first dose, which is the same as the Johnson & Johnson vaccine's only dose, and Ad5 for the second dose. Convidecia uses Ad5 for its only dose.[113]

Inactivated virus vaccines

Inactivated vaccines consist of virus particles that have been grown in culture and then are killed using a method such as heat or formaldehyde to lose disease producing capacity, while still stimulating an immune response.[114]

As of January 2021, authorized vaccines of this type are the Chinese CoronaVac,[115][116][117] BBIBP-CorV,[118] and WIBP-CorV; the Indian Covaxin; and the Russian CoviVac.[119] Vaccines in clinical trials include the Valneva COVID-19 vaccine.[120][121]

Subunit vaccines

Subunit vaccines present one or more antigens without introducing whole pathogen particles. The antigens involved are often protein subunits, but can be any molecule that is a fragment of the pathogen.[122]

As of April 2021, the two authorized vaccines of this type are the peptide vaccine EpiVacCorona[123] and RBD-Dimer.[3] Vaccines with pending authorizations include the Novavax COVID-19 vaccine,[124] SOBERANA 02 (a conjugate vaccine), and the Sanofi–GSK vaccine. The V451 vaccine was previously in clinical trials, which were terminated because it was found that the vaccine may potentially cause incorrect results for subsequent HIV testing.[125][126]

Other types

Additional types of vaccines that are in clinical trials include virus-like particle vaccines, multiple DNA plasmid vaccines,[127][128][129][130][131][132] at least two lentivirus vector vaccines,[133][134] a conjugate vaccine, and a vesicular stomatitis virus displaying the SARS‑CoV‑2 spike protein.[135]

Oral vaccines and intranasal vaccines are being developed and studied.[136]

Scientists investigated whether existing vaccines for unrelated conditions could prime the immune system and lessen the severity of COVID‑19 infection.[137] There is experimental evidence that the BCG vaccine for tuberculosis has non-specific effects on the immune system, but no evidence that this vaccine is effective against COVID‑19.[138]


Cumulative incidence curves for symptomatic COVID‑19 infections after the first dose of the Pfizer–BioNTech vaccine (tozinameran) or placebo in a double-blind clinical trial. (red: placebo; blue: tozinameran)[139]

Vaccine efficacy is the risk of getting the disease by vaccinated participants in a controlled trial compared with the risk of getting the disease by unvaccinated participants.[140] An efficacy of 0% means that the vaccine does not work (identical to placebo). An efficacy of 50% means that there are half as many cases of infection as in unvaccinated individuals.

It is not straightforward to compare the efficacies of the different vaccines because the trials were run with different populations, geographies, and variants of the virus.[141] In the case of COVID‑19, a vaccine efficacy of 67% may be enough to slow the pandemic, but this assumes that the vaccine confers sterilizing immunity, which is necessary to prevent transmission. Vaccine efficacy reflects disease prevention, a poor indicator of transmissibility of SARS‑CoV‑2 since asymptomatic people can be highly infectious.[142] The US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) set a cutoff of 50% as the efficacy required to approve a COVID‑19 vaccine.[143][144] Aiming for a realistic population vaccination coverage rate of 75%, and depending on the actual basic reproduction number, the necessary effectiveness of a COVID-19 vaccine is expected to need to be at least 70% to prevent an epidemic and at least 80% to extinguish it without further measures, such as social distancing.[145]

In efficacy calculations, symptomatic COVID-19 is generally defined as having both a positive PCR test and at least one or two of a defined list of COVID-19 symptoms, although exact specifications vary between trials.[citation needed] The trial location also affects the reported efficacy because different countries have different prevalences of SARS-CoV-2 variants.[citation needed] Ranges below are 95% confidence intervals unless indicated otherwise, and all values are for all participants regardless of age, according to the references for each of the trials. By definition, the absence of a confidence interval means that the accuracy of the estimates without an associated confidence interval is unknown to the public. Efficacy against severe COVID-19 is the most important, since hospitalizations and deaths are a public health burden whose prevention is a priority.[146] Authorized and approved vaccines have shown the following efficacies:

Vaccine Efficacy by severity of COVID-19 Trial location Refs
Mild or moderate[A] Severe without hospitalization or death[B] Severe with hospitalization or death[C]
Oxford–AstraZeneca 81% (6091%)[D] 100% (97.5% CI, 72100%) 100% Multinational [147]
76% (6882%)[E] 100% 100% United States [148]
Pfizer–BioNTech 95% (9098%)[F] Not reported Not reported Multinational [149]
Sputnik V 92% (8695%) 100% (94100%) 100% Russia [150]
BBIBP-CorV 78% (6586%) 100% 100% Multinational [151]
Moderna 94% (8997%)[G] 100%[H] 100%[H] United States [152]
Johnson & Johnson 66% (5575%)[I][J] 85% (5497%)[J] 100%[J][K] Multinational [153]
72% (5882%)[I][J] 86% (−9 to 100%)[J] 100%[J][K] United States
68% (4981%)[I][J] 88% (8100%)[J] 100%[J][K] Brazil
64% (4179%)[I][J] 82% (4695%)[J] 100%[J][K] South Africa
CoronaVac 51% (3662%)[L] 84% (5894%)[L] 100% (56100%)[L] Brazil [155][156][157]
84% (6592%) 100% 100% (20100%) Turkey [157]
Covaxin 78% (6188%)[L] 100%[L] 100%[L] India [158][159][unreliable medical source?]
Sputnik Light 79% Not reported Not reported Russia [160][unreliable medical source?]
Convidecia 66%[L] 91%[L] Not reported Multinational [161][unreliable medical source?]
Novavax 89% (7595%) 100%[M] 100%[M] United Kingdom [162][163][164]
60% (2080%) 100%[M] 100%[M] South Africa
90% Not reported Not reported United States
Not reported Not reported Mexico
  1. ^ Mild symptoms: fever, dry cough, fatigue, myalgia, arthralgia, sore throat, diarrhea, nausea, vomiting, headache, anosmia, ageusia, nasal congestion, rhinorrhea, conjunctivitis, skin rash, chills, dizziness. Moderate symptoms: mild pneumonia.
  2. ^ Severe symptoms without hospitalization or death for an individual, are any one of the following severe respiratory symptoms measured at rest on any time during the course of observation (on top of having either pneumonia, deep vein thrombosis, dyspnea, hypoxia, persistent chest pain, anorexia, confusion, fever above 38 °C (100 °F)), that however were not persistent/severe enough to cause hospitalization or death: Any respiratory rate ≥30 breaths/minute, heart rate ≥125 beats/minute, oxygen saturation (SpO2) ≤93% on room air at sea level, or partial pressure of oxygen/fraction of inspired oxygen (PaO2/FiO2) <300 mmHg.
  3. ^ Severe symptoms causing hospitalization or death, are those requiring treatment at hospitals or results in deaths: dyspnea, hypoxia, persistent chest pain, anorexia, confusion, fever above 38 °C (100 °F), respiratory failure, kidney failure, multiorgan dysfunction, sepsis, shock.
  4. ^ With twelve weeks or more between doses. For an interval of less than six weeks, the trial found an efficacy ≈55% (3370%).
  5. ^ With a four-week interval between doses. Efficacy is "at preventing symptomatic COVID-19".
  6. ^ Mild/Moderate COVID-19 symptoms observed in the Pfizer–BioNTech vaccine trials, were only counted as such for vaccinated individuals if they began more than seven days after their second dose, and required presence of a positive RT-PCR test result along with at least one of the following symptoms: fever; new or increased cough; new or increased shortness of breath; chills; new or increased muscle pain; new loss of taste or smell; sore throat; diarrhea; or vomiting.[149]
  7. ^ Mild/Moderate COVID-19 symptoms observed in the Moderna vaccine trials, were only counted as such for vaccinated individuals if they began more than 14 days after their second dose, and required presence of a positive RT-PCR test result along with at least two systemic symptoms (fever above 38ºC, chills, myalgia, headache, sore throat, new olfactory and taste disorder) or just one respiratory symptom (cough, shortness of breath or difficulty breathing, or clinical or radiographical evidence of pneumonia).[152]
  8. ^ a b Severe COVID-19 symptoms observed in the Moderna vaccine trials, were defined as symptoms having met the criteria for mild/moderate symptoms plus any of the following observations: Clinical signs indicative of severe systemic illness, respiratory rate ≥30 per minute, heart rate ≥125 beats per minute, SpO2 ≤93% on room air at sea level or PaO2/FIO2 <300 mm Hg; or respiratory failure or ARDS, (defined as needing high-flow oxygen, non-invasive or mechanical ventilation, or ECMO), evidence of shock (systolic blood pressure <90 mmHg, diastolic BP <60 mmHg or requiring vasopressors); or significant acute renal, hepatic, or neurologic dysfunction; or admission to an intensive care unit or death. No severe cases were detected for vaccinated individuals in the trials, compared with thirty in the placebo group (incidence rate 9.1 per 1000 person-years).[152]
  9. ^ a b c d Moderate cases.
  10. ^ a b c d e f g h i j k l Efficacy reported 28 days post-vaccination for the Johnson & Johnson single shot vaccine. A lower efficacy was found for the vaccinated individuals 14 days post-vaccination.[153]
  11. ^ a b c d No hospitalizations or deaths were detected 28 days post-vaccination for 19,630 vaccinated individuals in the trials, compared with 16 hospitalizations reported in the placebo group of 19,691 individuals (incidence rate 5.2 per 1000 person-years)[153] and seven COVID-19 related deaths for the same placebo group.[154]
  12. ^ a b c d e f g h These Phase III data have not been published or peer reviewed.
  13. ^ a b c d No cases detected in trial.


The real-world studies of vaccine effectiveness measure to which extent a certain vaccine has succeeded in preventing COVID-19 infection, symptoms, hospitalization and death for the vaccinated individuals in a large population under routine conditions that are less than ideal.[165]

  • In Israel, among the 715,425 individuals vaccinated by the Moderna or Pfizer-BioNTech vaccines during the period 20 December 2020, to 28 January 2021, it was observed for the period starting seven days after the second shot, that only 317 people (0.04%) became sick with mild/moderate Covid-19 symptoms and only 16 people (0.002%) were hospitalized.[166]
  • The Pfizer-BioNTech and Moderna Covid-19 vaccines provide highly effective protection, according to a report from the US Centers for Disease Control and Prevention (CDC). Under real-world conditions, mRNA vaccine effectiveness of full immunization (≥14 days after second dose) was 90% against SARS-CoV-2 infections regardless of symptom status; vaccine effectiveness of partial immunization (≥14 days after first dose but before second dose) was 80%.[167]
  • 15,121 health care workers from 104 hospitals in England, that all had tested negative for COVID-19 antibodies prior of the study, were followed by RT-PCR tests twice a week from 7 December 2020 to 5 February 2021, during a time when the Alpha variant (lineage B.1.1.7) was in circulation as the dominant variant. The study compared the positive results for the 90.7% vaccinated share of their cohort with the 9.3% unvaccinated share, and found that the Pfizer-BioNTech vaccine reduced all infections (including asymptomatic), by 72% (58-86%) three weeks after the first dose and 86% (76-97%) one week after the second dose.[168][needs update]
  • A study of the general population in Israel conducted from 17 January to 6 March 2021, during a time when the Alpha variant was in circulation as the dominant variant, found that the Pfizer vaccine reduced asymptomatic COVID-19 infections by 94% and symptomatic COVID-19 infections by 97%.[169]
  • A study, among pre-surgical patients across the Mayo Clinic system in the United States, showed that mRNA vaccines were 80% protective against asymptomatic infections.[170]
  • A study in England found that a single dose of the Oxford–AstraZeneca COVID-19 vaccine is about 73% (2790%) effective in people aged 70 and older.[171]
Vaccine Effectiveness by severity of COVID-19 Study location Refs
Asymptomatic Symptomatic Hospitalization Death
Oxford–AstraZeneca Not reported 89% (7894%) Not reported England [172]
Pfizer–BioNTech 85% (7496%) Not reported England [173]
90% (6897%) Not reported 100%[i] United States [167]
92% (8895%) 94% (8798%) 87% (55100%) 97% Israel [174][169]
80%[ii] 97%[ii] 94%[ii] Uruguay [175]
Sputnik V Not reported 98% Not reported Russia [176][177]
Moderna 90% (6897%) Not reported 100%[i] United States [167]
CoronaVac Not reported 65% 87% 86% Chile [178][179]
Not reported 94% 96% 98% Indonesia [180][181]
65% 94% 95% Uruguay [175]
80% 86% 95% Brazil [182][183]
  1. ^ a b No cases detected in study.
  2. ^ a b c Participants aged 80 and older.


World Health Organization video describing how variants proliferate in unvaccinated areas.

The potential emergence of a SARS-CoV-2 variant that is moderately or fully resistant to the antibody response elicited by the current generation of COVID-19 vaccines may necessitate modification of the vaccines.[184] Trials indicate many vaccines developed for the initial strain have lower efficacy for some variants against symptomatic COVID-19.[185] As of February 2021, the US Food and Drug Administration believed that all FDA authorized vaccines remained effective in protecting against circulating strains of SARS-CoV-2.[184]

Alpha (lineage B.1.1.7)

Limited evidence from various preliminary studies reviewed by the WHO have indicated retained efficacy/effectiveness against disease from Alpha with the Oxford–AstraZeneca vaccine, Pfizer–BioNTech and Novavax, with no data for other vaccines yet. Relevant to how vaccines can end the pandemic by preventing asymptomatic infection, they have also indicated retained antibody neutralization against Alpha with most of the widely distributed vaccines (Sputnik V, Pfizer–BioNTech, Moderna, CoronaVac, BBIBP-CorV, Covaxin), minimal to moderate reduction with the Oxford–AstraZeneca and no data for other vaccines yet.[186]

In December 2020, a new SARS‑CoV‑2 variant, the Alpha variant or lineage B.1.1.7, was identified in the UK.[187]

Early results suggest protection to the variant from the Pfizer-BioNTech and Moderna vaccines.[188][189]

One study indicated that the Oxford–AstraZeneca COVID-19 vaccine had an efficacy of 42–89% against Alpha, versus 71–91% against other variants.[190]

Preliminary data from a clinical trial indicates that the Novavax vaccine is ~96% effective for symptoms against the original variant and ~86% against Alpha.[191]

Beta (lineage B.1.351)

Limited evidence from various preliminary studies reviewed by the WHO have indicated reduced efficacy/effectiveness against disease from Beta with the Oxford–AstraZeneca vaccine (possibly substantial), Novavax (moderate), Pfizer–BioNTech and Johnson & Johnson (minimal), with no data for other vaccines yet. Relevant to how vaccines can end the pandemic by preventing asymptomatic infection, they have also indicated possibly reduced antibody neutralization against Beta with most of the widely distributed vaccines (Oxford–AstraZeneca, Sputnik V, Johnson & Johnson, Pfizer–BioNTech, Moderna, Novavax; minimal to substantial reduction) except CoronaVac and BBIBP-CorV (minimal to modest reduction), with no data for other vaccines yet.[186]

Moderna has launched a trial of a vaccine to tackle the Beta variant or lineage B.1.351.[192] On 17 February 2021, Pfizer announced neutralization activity was reduced by two-thirds for this variant, while stating that no claims about the efficacy of the vaccine in preventing illness for this variant could yet be made.[193] Decreased neutralizing activity of sera from patients vaccinated with the Moderna and Pfizer-BioNTech vaccines against Beta was later confirmed by several studies.[189][194] On 1 April 2021, an update on a Pfizer/BioNTech South African vaccine trial stated that the vaccine was 100% effective so far (i.e., vaccinated participants saw no cases), with six of nine infections in the placebo control group being the Beta varian.[195]

In January 2021, Johnson & Johnson, which held trials for its Ad26.COV2.S vaccine in South Africa, reported the level of protection against moderate to severe COVID-19 infection was 72% in the United States and 57% in South Africa.[196]

On 6 February 2021, the Financial Times reported that provisional trial data from a study undertaken by South Africa's University of the Witwatersrand in conjunction with Oxford University demonstrated reduced efficacy of the Oxford–AstraZeneca COVID-19 vaccine against the variant.[197] The study found that in a sample size of 2,000 the AZD1222 vaccine afforded only "minimal protection" in all but the most severe cases of COVID-19.[198] On 7 February 2021, the Minister for Health for South Africa suspended the planned deployment of about a million doses of the vaccine whilst they examine the data and await advice on how to proceed.[199][200]

In March 2021, it was reported that the "preliminary efficacy" of the Novavax vaccine (NVX-CoV2373) against Beta for mild, moderate, or severe COVID-19[201] for HIV-negative participants is 51%.[medical citation needed]

Gamma (lineage P.1)

Limited evidence from various preliminary studies reviewed by the WHO have indicated likely retained efficacy/effectiveness against disease from Gamma with CoronaVac and BBIBP-CorV, with no data for other vaccines yet. Relevant to how vaccines can end the pandemic by preventing asymptomatic infection, they have also indicated retained antibody neutralization against Gamma with Oxford–AstraZeneca and CoronaVac (no to minimal reduction) and slightly reduced neutralization with Pfizer–BioNTech and Moderna (minimal to moderate reduction), with no data for other vaccines yet.[186]

The Gamma variant or lineage P.1 variant (also known as 20J/501Y.V3), initially identified in Brazil, seems to partially escape vaccination with the Pfizer-BioNTech vaccine.[194]

Delta (lineage B.1.617)

Limited evidence from various preliminary studies reviewed by the WHO have indicated likely retained efficacy/effectiveness against disease from Delta with the Oxford–AstraZeneca vaccine and Pfizer–BioNTech, with no data for other vaccines yet. Relevant to how vaccines can end the pandemic by preventing asymptomatic infection, they have also indicated reduced antibody neutralization against Delta with Oxford–AstraZeneca (substantial reduction), Pfizer–BioNTech and Covaxin (modest to moderate reduction), with no data for other vaccines yet.[186]

In October 2020, a new variant was discovered in India, which was named lineage B.1.617. There were very few detections until January 2021, but by April it had spread to at least 20 countries in all continents except Antarctica and South America.[202][203][204] Among some 15 defining mutations, it has spike mutations D111D (synonymous), G142D,[medical citation needed] P681R, E484Q[205] and L452R,[206] the latter two of which may cause it to easily avoid antibodies.[207] The variant has frequently been referred to as a 'Double mutant', even though in this respect it is not unusual.[206] In an update on 15 April 2021, PHE designated lineage B.1.617 as a 'Variant under investigation', VUI-21APR-01.[208] On 6 May 2021, Public Health England escalated lineage B.1.617.2 from a Variant Under Investigation to a Variant of Concern based on an assessment of transmissibility being at least equivalent to the Alpha variant.[209]

Trial and authorization status

Phase I trials test primarily for safety and preliminary dosing in a few dozen healthy subjects, while Phase II trials – following success in Phase I – evaluate immunogenicity, dose levels (efficacy based on biomarkers) and adverse effects of the candidate vaccine, typically in hundreds of people.[38][39] A Phase I–II trial consists of preliminary safety and immunogenicity testing, is typically randomized, placebo-controlled, while determining more precise, effective doses.[39] Phase III trials typically involve more participants at multiple sites, include a control group, and test effectiveness of the vaccine to prevent the disease (an "interventional" or "pivotal" trial), while monitoring for adverse effects at the optimal dose.[38][39] Definition of vaccine safety, efficacy, and clinical endpoints in a Phase III trial may vary between the trials of different companies, such as defining the degree of side effects, infection or amount of transmission, and whether the vaccine prevents moderate or severe COVID‑19 infection.[40][210][211]

A clinical trial design in progress may be modified as an "adaptive design" if accumulating data in the trial provide early insights about positive or negative efficacy of the treatment.[212][213] Adaptive designs within ongoing Phase II–III clinical trials on candidate vaccines may shorten trial durations and use fewer subjects, possibly expediting decisions for early termination or success, avoiding duplication of research efforts, and enhancing coordination of design changes for the Solidarity trial across its international locations.[212][214]

List of authorized and approved vaccines

National regulatory authorities have granted emergency use authorizations for fifteen vaccines. Six of those have been approved for emergency or full use by at least one WHO-recognized stringent regulatory authority. Biologic License Applications for the Pfizer–BioNTech and Moderna COVID-19 vaccines have been submitted to the US Food and Drug Administration (FDA).[215][216]

Vaccines authorized for emergency use or approved for full use
Vaccine, developers/sponsors Country of origin Type (technology) Doses, interval Storage temperature Pre-marketing study (participants) Postmarketing study (participants) Authorization
Oxford–AstraZeneca COVID-19 vaccine (Vaxzevria, Covishield)[217][a][b][105][106][107]
University of Oxford, AstraZeneca, CEPI
United Kingdom, Sweden Adenovirus vector (ChAdOx1)[105] 2 doses
4–12 weeks[221]
2–8 °C[222] Phase III (30,000)
Interventional; randomized, placebo-controlled study for efficacy, safety, and immunogenicity.[223]
Overall efficacy of 76% after the first dose and 81% after a second dose taken 12 weeks or more after the first.[147]
May 2020 – Aug 2021, Brazil (5,000),[224] United Kingdom, India[225]
Phase IV (10,000)[226]
Interventional, non-randomized
Feb 2021 – Dec 2024, Denmark
Full (2)
Emergency (170)
Pfizer–BioNTech COVID-19 vaccine (Comirnaty)[96][97][98]
BioNTech, Pfizer
Germany, United States RNA (modRNA in lipid nanoparticles)[96] 2 doses
3–4 weeks[227][c]
−70±10 °C[d]
Phase III (43,448)
Randomized, placebo-controlled.
Positive results from an interim analysis were announced on 18 November 2020[232] and published on 10 December 2020 reporting an overall efficacy of 95%.[233][234]
Jul–Nov 2020,[235][140] Germany, United States
Phase IV (10,000)[226]
Interventional, non-randomized
Feb 2021 – Dec 2024, Denmark
Full (5)
Emergency (109)
Sputnik V COVID-19 vaccine (Gam-COVID-Vac)
Gamaleya Research Institute of Epidemiology and Microbiology
Russia Adenovirus vector (recombinant Ad5 and Ad26)[236] 2 doses
3 weeks[237]
−18 °C[e]
Phase III (40,000)
Randomized double-blind, placebo-controlled to evaluate efficacy, immunogenicity, and safety.[239]
Interim analysis from the trial was published in The Lancet, indicating 91.6% efficacy without unusual side effects.[150]
Aug 2020 – May 2021, Russia, Belarus,[240] India,[241][242] Venezuela,[243][244] United Arab Emirates[245]
Full (2)
Emergency (71)
Sinopharm: Beijing Institute of Biological Products
China Inactivated SARS‑CoV‑2 (vero cells)[118] 2 doses
3–4 weeks[246]
2–8 °C[247] Phase III (48,000)
Randomized, double-blind, parallel placebo-controlled, to evaluate safety and protective efficacy.
Peer-reviewed results indicate 78.1% efficacy against symptomatic COVID-19.[151]
Jul 2020 – Jul 2021, United Arab Emirates, Bahrain, Jordan,[248] Argentina,[249] Morocco,[250] Peru[251]
Full (4)
Emergency (71)
Moderna COVID-19 vaccine (mRNA-1273, TAK-919)[99][100]
United States RNA (modRNA in lipid nanoparticles)[252] 2 doses
4 weeks[253][c]
−20±5 °C[254]
Phase III (30,000)
Interventional; randomized, placebo-controlled study for efficacy, safety, and immunogenicity.
Positive results from an interim analysis were announced on 15 November 2020[255] and published on 30 December 2020 reporting an overall efficacy of 94%.[256]
Jul 2020 – Oct 2022, United States
Phase IV (10,000)[226]
Interventional, non-randomized
Feb 2021 – Dec 2024, Denmark
Full (2)
Emergency (73)
Johnson & Johnson COVID-19 vaccine[109][110]
Janssen Vaccines (Johnson & Johnson), BIDMC
United States, Netherlands Adenovirus vector (recombinant Ad26)[257] 1 dose[258] 2–8 °C[258] Phase III (40,000)
Randomized, double-blinded, placebo-controlled
Positive results from an interim analysis were announced on 29 January 2021. J&J reports an efficacy of 66% against mild and moderate symptoms, and 85% against severe symptoms. Further, the mild and moderate efficacy ranged from 64% in South Africa to 72% in the United States.[259][153]
Jul 2020 – ? 2023, United States, Argentina, Brazil, Chile, Colombia, Mexico, Peru, the Philippines, South Africa, Ukraine
Full (1)
Emergency (77)
China Inactivated SARS‑CoV‑2 (vero cells)[115] 2 doses
2–3 weeks[260][261]
2–8 °C[262] Phase III (33,620)
Double-blind, randomized, placebo-controlled to evaluate efficacy and safety.
Final Phase III results from Turkey showed an efficacy of 83.5%.[157] A Chilean study showed 65% efficacy against symptomatic cases, 87% against hospitalization, 90% against ICU admissions, and 86% against deaths.[178][179] Brazil announced results showing 50.7% effective at preventing symptomatic infections, 83.7% effective in preventing mild cases, and 100% effective in preventing severe cases.[261]
July 2020 – Oct 2021, Brazil (15,000);[263] Aug 2020 – January 2021, Indonesia (1,620); Oct – Nov 2020, China (1,040);[264] Nov 2020 – Jan 2022,[265] Chile (3,000);[266] Apr 2021 – Jun 2022, the Philippines (phase II/III: 352);[267] Sep 2020 – Feb 2021, Turkey (13,000);[268]
Phase IV (37,867)[269][270]
Feb 2021 – Feb 2022, Serrana (São Paulo) (27,711); Mar 2021 – Mar 2022, Manaus (10,156)
Full (1)
Emergency (47)
BBV152 (Covaxin)
Bharat Biotech, Indian Council of Medical Research
India Inactivated SARS‑CoV‑2 (vero cells)[271] 2 doses
4 weeks[272]
2–8 °C[272] Phase III (25,800)
Randomised, observer-blinded, placebo-controlled[273]
Bharat Biotech reported an interim efficacy is 78% for its phase 3 trial.[274]
Nov 2020 – Mar 2021, India.
Full (0)
Emergency (19)
Sputnik Light
Gamaleya Research Institute of Epidemiology and Microbiology[275]
Russia Adenovirus vector (recombinant Ad26)[276] 1 dose[276] 2–8 °C[277] Phase III (7,000)[278]
Randomised, double-blind, placebo-controlled trial[276]
Feb  – Dec 2021, Russia (6,000)
Full (0)
Emergency (9)
Ad5-nCoV (Convidecia)
CanSino Biologics, Beijing Institute of Biotechnology of the Academy of Military Medical Sciences
China Adenovirus vector (recombinant Ad5)[279] 1 dose[161] 2–8 °C[161] Phase III (40,000)
Global multi-center, randomized, double-blind, placebo-controlled to evaluate efficacy, safety and immunogenicity.
In February 2021, interim analysis from global trials showed an efficacy of 65.7% against moderate cases of COVID-19 and 90.98% efficacy against severe cases.[161]
Mar–Dec 2020, China; Sep 2020 – Dec 2021, Pakistan; Sep–Nov 2020, Russia,[280] China, Argentina, Chile;[281] Mexico;[282] Pakistan;[283] Saudi Arabia[284][285]
Full (1)
Emergency (8)
Sinopharm: Wuhan Institute of Biological Products
China Inactivated SARS‑CoV‑2 (vero cells) 2 doses
3 weeks[286][287][288]
2–8 °C Phase III (51,600)
Randomized, double-blind, placebo-controlled[289]
Peer-reviewed results indicate 72.8% efficacy against symptomatic COVID-19.[151]
Jul 2020 – Mar 2021, Bahrain, Egypt, Jordan, United Arab Emirates;[286] Sep 2020 – Sep 2021, Peru;[287] Sep 2020 – Dec 2020, Morocco[290]
Full (1)
Emergency (4)
Vector Institute
Russia Subunit (peptide)[291] 2 doses
3 weeks[291]
2–8 °C[293] Phase III (40,150(planned), 3,000(started))[294]
Randomized double-blind, placebo-controlled to evaluate efficacy, immunogenicity, and safety
Nov 2020 – Dec 2021, Russia (3,000) [295][296][297][298]
Full (1)
Emergency (2)
ZF2001 (RBD-Dimer)[3]
Anhui Zhifei Longcom Biopharmaceutical Co. Ltd.
China Subunit (recombinant) 3 doses
30 days[299][300]
2–8 °C[301] Phase III (29,000)
Randomized, double-blind, placebo-controlled[299]
Dec 2020 – Apr 2022, China, Ecuador, Indonesia, Malaysia, Pakistan, Uzbekistan[302][303]
Full (0)
Emergency (2)
The Chumakov Centre at the Russian Academy of Sciences
Russia Inactivated SARS‑CoV‑2 (vero cells)[305] 2 doses
2 weeks[306]
2–8 °C[306] Phase III (32,000)[307]
Double-blind, randomized, placebo-controlled to evaluate efficacy and safety.
May 2021 – ?, Russia (3,000)[308]
Full (0)
Emergency (1)
QazCovid-in (QazVac)[309]
Research Institute for Biological Safety Problems
Kazakhstan Inactivated SARS‑CoV‑2 2 doses
3 weeks[310]
2–8 °C[311] Phase III (3,000)
Randomised, blind, placebo-controlled trial[312]
Mar 2021 – Jul 2021, Kazakhstan[312]
Full (0)
Emergency (1)
Minhai COVID-19 vaccine
Minhai Biotechnology Co., Shenzhen Kangtai Biological Products Co. Ltd.
China Inactivated SARS‑CoV‑2 (vero cell) 2 doses
4 weeks[313]
2–8 °C Phase III (28,000)[313]
Multi-national, Randomized, Double-blind, Placebo-controlled.
April–Nov 2021, China, the Philippines
Full (0)
Emergency (1)
COVIran Barakat[314]
Barakat Pharmaceutical Group, Shifa Pharmed Industrial Group
Iran Inactivated SARS‑CoV‑2 2 doses
4 weeks[315]
2–8 °C Phase III (52,000)
Phase II-IIIa (20,000): Randomized, double-blind, parallel arms, placebo-controlled.[315]
Phase IIIb (32,000)[316]
Mar–Jun 2021, Iran
Full (0)
Emergency (1)
Chinese Academy of Medical Sciences COVID-19 vaccine[317][318]
Chinese Academy of Medical Sciences
China Inactivated SARS‑CoV‑2 2 doses
2 weeks[318]
2–8 °C Phase III (34,020)
Randomized, double-blinded, single-center, placebo-controlled
Jan–Sep 2021, Brazil, Malaysia
Full (0)
Emergency (1)

Vaccine candidates in human trials

COVID‑19 candidate vaccines in Phase I–III trials[3][319][320]
Vaccine candidates,
developers, and sponsors
Country of origin Type (technology) Current phase (participants)
Completed phase[f] (participants)
Immune response
Pending authorization
Novavax COVID-19 vaccine (Covovax, TAK-019)[124][321]
Novavax, CEPI
United States Subunit[322][323][324]/virus-like particle[325][326] (SARS‑CoV‑2 recombinant spike protein nanoparticle with adjuvant) Phase III (48,000)
Randomised, observer-blinded, placebo-controlled trial[327]
Sep 2020 – Jan 2021, UK (15,000); Dec 2020 – Jun 2023, US, Mexico, (33,000);[328] India[329]
Phase I–II (131)
IgG and neutralizing antibody response with adjuvant after booster dose.[330]
Emergency (8)
Sanofi–GSK COVID-19 vaccine (VAT00008)
Sanofi Pasteur, GSK
France, United Kingdom Subunit Phase III (37,430)[340]
A Parallel-group, Phase III, Multi-stage, Modified Double-blind, Multi-armed Study to Assess the Efficacy, Safety, and Immunogenicity of Two SARS-CoV-2 Adjuvanted Recombinant Protein Vaccines (Monovalent and Bivalent) for Prevention Against COVID-19 in Adults 18 Years of Age and Older.
May 2021 – Jan 2023, Kenya,[341] Mexico,[342] United States
Phase I–II (1,160)
Phase I-IIa (440): Immunogenicity and Safety of SARS-CoV-2 Recombinant Protein Vaccine Formulations (With or Without Adjuvant) in Healthy Adults 18 Years of Age and Older.[343]
Phase IIb (720): Immunogenicity and Safety of SARS-CoV-2 Recombinant Protein Vaccine With AS03 Adjuvant in Adults 18 Years of Age and Older.[344]
Sep 2020 – Apr 2022, United States
Emergency (4)
CureVac COVID-19 vaccine (CVnCoV)
CureVac, CEPI
Germany RNA (unmodified RNA)[349] Phase III (40,400)[350][351][352][353]
Phase 2b/3 (36,500): Multicenter efficacy and safety trial in adults.
Phase 3 (2,520): Randomized, observer-blinded, placebo-controlled.
Phase 3 (180+1,200): Open-label.
Nov 2020 – Sep 2021, Argentina, Belgium, Colombia, Dominican Republic, France, Germany, Mexico, Netherlands, Panama, Peru, Spain
Phase I–II (944)[354][355]
Phase I (284): Partially blind, controlled, dose-escalation to evaluate safety, reactogenicity and immunogenicity.
Phase IIa (660):Partially observer-blind, multicenter, controlled, dose-confirmation.
Jun 2020 – Oct 2021, Belgium (phase I), Germany (phase I), Panama (phase IIa), Peru (phase IIa)
Emergency (2)
Medicago, GSK
Canada, United Kingdom Virus-like particles[g] (recombinant, plant-based with AS03) Phase III (30,918)
Event-driven, randomized, observer blinded, placebo-controlled[360]
Nov 2020 – Dec 2021, Canada
Phase I (180)
Neutralizing antibodies at day 42 after the first injection (day 21 after the second injection) were at levels 10x that of COVID-19 survivors.
Jul 2020 – Sept 2021, Canada[361]
Emergency (1)
Instituto Finlay de Vacunas
Cuba Subunit (conjugate) Phase III (44,010)[363][364]
Multicenter, adaptive, parallel-group, randomized, placebo-controlled, double-blind
Mar–May 2021, Cuba, Iran, Venezuela[365]
Phase I–II (950)[366][367]
Phase I (40): Non-randomized controlled trial. Masking: Open. Control group: Uncontrolled. Study design: Adaptive, sequential
Phase II (910): Randomized controlled trial. Masking: Double Blind. Control group: Placebo. Study design: Parallel.
Nov 2020 – Mar 2021, Cuba
Emergency (1)
France Inactivated SARS‑CoV‑2 Phase III (4,019)[369][370]
Randomized, observer-blind, controlled.
Apr–Jul 2021, United Kingdom
Phase I–II (3,039)
Phase I/II (153): Randomized, multi-center, double-blinded.
Phase II (2886): A randomised, phase II UK multi-centre study to determine reactogenicity and immunogenicity of booster vaccination against ancestral and novel variants of SARS-CoV-2.[371]
Dec 2020 – Jun 2021, United Kingdom
Emergency (1)
Cadila Healthcare,
Biotechnology Industry Research Assistance Council
India DNA (plasmid expressing SARS‑CoV‑2 S protein) Phase III (28,216)[373][374]
Randomised, blind, placebo-controlled trial[375]
Jan–May 2021, India[376]
Phase I–II (1,000)
Interventional; randomized, double-blind, placebo-controlled[377][375]
Jul 2020 – Jan 2021, India
Emergency (1)
Nanogen Pharmaceutical Biotechnology JSC
Vietnam Subunit (SARS‑CoV‑2 recombinant spike protein with aluminum adjuvant)[380][381] Phase III (13,000)[382][383]
Adaptive, multicenter, randomized, double-blind, placebo-controlled
Jun 2021 – Jul 2022, Vietnam
Phase I–II (620)[384]
Phase I (60): Open label, dose escalation.
Phase II (560): Randomization, double-blind, multicenter, placebo-controlled.
Dec 2020 – Jun 2021, Vietnam
Emergency (1)
MVC COVID-19 Vaccine (MVC-COV1901)
Medigen Vaccine Biologics, Dynavax Technologies[386]
Taiwan Subunit Phase II (4,152)[387][388][389]
Phase IIa (3,752): Prospective, double-blinded, multi-center, multi-regional.
Phase IIb (400): Prospective, randomized, double-blind, dose-comparison, multi-center.
Dec 2020 – Sep 2021, Taiwan, Vietnam (phase IIa)
Phase I (45)[390]
Prospective, open-labeled, single-center
Oct 2020 – Jan 2021, Taiwan
Emergency (1)
Center for Genetic Engineering and Biotechnology
Cuba Subunit Phase III (48,000)[392]
Multicenter, randomized, double-blind, placebo-controlled.
Mar–Jul 2021, Cuba
Phase I–II (132)[393]
Randomized, double-blind, placebo-controlled, factorial.
Nov 2020 – May 2021, Cuba
West China Hospital COVID-19 vaccine
Jiangsu Province Centers for Disease Control and Prevention, West China Hospital, Sichuan University
China Subunit (recombinant with Sf9 cell) Phase III (40,000)[394][395]
Multicenter, randomized, double-blind, placebo-controlled.
Jun 2021 – Feb 2022, China, the Philippines
Phase I–II (5,005)[396][397][398]
Phase I (45): Single-center, Randomized, Placebo-controlled, Double-blind.
Phase IIa (960):Single-center, Randomized, Double-Blinded, Placebo-Controlled.
Phase IIb (4,000):Single-center, Randomized, Double-Blinded, Placebo-Controlled.
Aug 2020 – May 2021, China
Walvax COVID-19 vaccine (ARCoV)[399]
PLA Academy of Military Science, Walvax Biotech,[400] Suzhou Abogen Biosciences
China RNA Phase III (28,000)
Multi-center, Randomized, Double-blind, Placebo-controlled
May–Oct 2021, China,[401] Mexico
Phase I–II (588)
Phase I (168)
Phase II (420)
Jun 2020 – Mar 2022, China[402]
Bio E COVID-19 (Corbevax)[403][404][405]
Biological E. Limited, Baylor College of Medicine,[406] CEPI
India, United States Subunit (using an antigen) Phase III (1,268)[407]
Apr – Aug 2021, India
Phase I–II (360)[408]
Randomized, Parallel Group Trial
Nov 2020 – Feb 2021, India
Clover Biopharmaceuticals,[411][412] Dynavax Technologies,[413] CEPI
China Subunit (spike protein trimeric subunit with combined CpG 1018 and aluminium adjuvant) Phase II–III (22,000)
Randomized, double-blind, controlled
Mar 2021 – Jul 2022, Belgium, Brazil, Colombia, Dominican Republic, Germany, Nepal, Panama, the Philippines, Poland, South Africa
Phase I (150)
Jun–Oct 2020, Perth
United Biomedical,Inc, COVAXX, DASA
Brazil, United States Subunit Phase II–III (11,170)[414][415]
Phase IIa (3,850): Placebo-controlled, Randomized, Observer-blind Study.
Phase IIb-III (7,320): Randomized, Multicenter, Double-Blind, Placebo Controlled, Dose-Response.
Jan 2021 – Mar 2023, Taiwan
Phase I (60)[416]
Open-label study
Sep 2020 – Jan 2021, Taiwan
ReiThera, Lazzaro Spallanzani National Institute for Infectious Diseases
Italy Adenovirus vector (modified gorilla adenovirus vector, GRAd) Phase II–III (10,300)[419][420]
Randomized, stratified, observer-blind, placebo-controlled.
Mar–May 2021, Italy
Phase I (90)[421]
Subjects (two groups: 18–55 and 65–85 years old) randomly receiving one of three escalating doses of GRAd-COV2 or a placebo, then monitored over a 24-week period. 93% of subjects who received GRAd-COV2 developed anti-bodies.
Aug–Dec 2020, Rome
Livzon Mabpharm, Inc.
China Subunit Phase II (880)[422]
Randomized, double-blind, and placebo-controlled.
Mar–May 2021, China
Phase I (180)[423]
Single-center, randomized, double-blind and placebo-controlled.
Feb–Mar 2021, China
DelNS1-2019-nCoV-RBD-OPT (DelNS1-nCoV-RBD LAIV)
Beijing Wantai Biological Pharmacy, University of Hong Kong
China, Hong Kong Viral vector Phase II (720)[424]
Nov 2020 – Dec 2021, China
Phase I (60)[425]
Sep 2020 – Oct 2021, China
Razi Cov Pars
Razi Vaccine and Serum Research Institute
Iran Subunit Phase II (500)[426]
Two parallel groups, randomized, double blind, placebo controlled.
Apr–Jun 2021, Iran
Phase I (133)[427]
Randomized, double blind, placebo controlled.
Jan–Mar 2021, Iran
Organization of Defensive Innovation and Research
Iran Inactivated SARS‑CoV‑2 Phase II (500)[428]
Randomized, double blind, controlled trial with parallel design.
Jun–Jul 2021, Iran
Phase I (135)[429]
Randomized, double blind, controlled trial with factorial design.
Mar–Apr 2021, Iran
Zhongyianke Biotech–Liaoning Maokangyuan Biotech COVID-19 vaccine
Zhongyianke Biotech, Liaoning Maokangyuan Biotech, Academy of Military Medical Sciences
China Subunit (Recombinant) Phase II (480)[430]
Single-center, randomized, double blinded, placebo controlled.
Mar–Jul 2021, China
Phase I (216)[431]
Randomized, placebo-controlled, double-blind.
Oct 2020 – Apr 2021, China
Vaxine Pty Ltd[433]
Australia Subunit (recombinant protein) Phase II (400)[434]
Randomized, Two-armed, Double-blind, Placebo controlled.
May – Jul 2021, Iran
Phase I (40)
Jun 2020 – Jul 2021, Adelaide
Health Institutes of Turkey
Turkey Inactivated SARS‑CoV‑2 Phase II (250)[435]
Phase 2 Study for the Determination of Efficacy, Immunogenicity and Safety of Two Different Strengths of the Inactivated COVID-19 Vaccine ERUCOV-VAC, in a Placebo Controlled, Randomized, Double Blind Study Design.
Feb–Apr 2021, Turkey
Phase I (44)[436]
Study for the Determination of Safety and Immunogenicity of Two Different Strengths of the Inactivated COVID-19 Vaccine ERUCOV-VAC, Given Twice Intramuscularly to Healthy Volunteers, in a Placebo Controlled Study Design.
Nov 2020 – Mar 2021, Turkey
Inovio COVID-19 Vaccine (INO-4800)[128][129]
Inovio, CEPI, Korea National Institute of Health, International Vaccine Institute
South Korea, United States DNA vaccine (plasmid delivered by electroporation) Phase II–III (7,218)
Phase II/III (6,578): Randomized, placebo-controlled, multi-center.[437]
Phase IIa (640): Randomized, double-blinded, placebo-controlled, dose-finding.[438]
Nov 2020 – Sep 2022, United States (phase II/III)[h] China (phase IIa)
Phase I–II (280)
Phase Ia (120): Open-label trial.
Phase Ib-IIa (160): Dose-Ranging Trial.[439]
April 2020 – Feb 2022, United States, South Korea (phase Ib-IIa)
AnGes Inc.,[441] AMED
Japan DNA vaccine (plasmid) Phase II–III (500)
Randomized, double-blind, placebo controlled[442]
Nov 2020 – Apr 2021, Japan
Phase I–II (30)
Randomized/non-randomized, single-center, two doses
Jun–Nov 2020, Osaka
National Vaccine and Serum Institute, Lanzhou Institute of Biological Products Co., Ltd., Beijing Zhong Sheng Heng Yi Pharmaceutical Technology Co., Ltd., Zhengzhou University
China Subunit (Recombinant) Phase I–II (3,580)[443]
Phase I/II Clinical Trial to Evaluate the Safety, Tolerability and Immunogenicity of Recombinant SARS-CoV-2 Vaccine (CHO Cell) in Healthy People Aged 3 Years and Older.
Apr 2021 – Oct 2022, China
IIBR-100 (Brilife)[135]
The Israel Institute for Biological Research
Israel Vesicular stomatitis vector (recombinant) Phase I–II (1,040)[444]
Oct 2020 – May 2021, Israel
Arcturus COVID-19 vaccine (ARCT-021)[445][446]
Arcturus Therapeutics, Duke–NUS Medical School
United States, Singapore RNA Phase I–II (798)
Phase I/II (92): Randomized, double-blinded, placebo controlled
Phase IIa (106): Open label extension[447]
Phase IIb (600): Randomized, observer-blind, placebo-controlled[448]
Aug 2020 – Apr 2022, Singapore, United States (phase IIb)
Variation Biotechnologies
United States Virus-like particle Phase I–II (780)[450]
Randomized, observer-blind, dose-escalation, placebo-controlled
Mar 2021 – Jun 2022, Canada
Mahidol University, University of Texas at Austin
Thailand, United States Viral vector Phase I–II (460)[451]
Randomized, placebo-controlled, observer-blind.
Mar 2021 – Apr 2022; Brazil, Mexico, Thailand, Vietnam[452]
Sanofi–Translate Bio COVID-19 vaccine (MRT5500)[453]
Sanofi Pasteur and Translate Bio
France, United States RNA Phase I–II (415)[454]
Immunogenicity and Safety of the First-in-Human SARS-CoV-2 mRNA Vaccine Formulation in Healthy Adults 18 Years of Age and Older.
Mar 2021 – May 2022, United States
Institute of Vaccines and Medical Biologicals
Vietnam Viral vector/Egg-based, inactivated, whole chimeric Newcastle Disease Virus (NDV) expressing membrane-anchored pre-fusion-stabilized trimeric SARS-CoV-2 S protein (Hexapro) + CpG 1018.[456] Phase I–II (420)[457][458]
Phase I-II (120-300):Randomized, placebo-controlled, observer-blind.
Mar 2021 – May 2022, Vietnam
EuBiologics Co
South Korea Subunit Phase I–II (280)
Dose-exploration, randomized, observer-blind, placebo-controlled
Feb 2021 – Mar 2022, the Philipppines (phase II), South Korea (phase I/II)
United Kingdom Virus-like particle Phase I–II (280)[460]
Randomized, placebo-controlled, multi-center.
Aug 2020 – ?, Australia
GX-19 (GX-19N)[131][461][132]
Genexine consortium,[462][463] International Vaccine Institute
South Korea DNA vaccine Phase I–II (410)
Phase I-II (170+210+30): Multi-center, open-label, single arm, randomized, double-blind, placebo-controlled
Jun 2020 – Mar 2021, Seoul
AIVITA Biomedical, Inc., Ministry of Health (Indonesia)
United States, Indonesia Viral vector Phase I–II (202)[464][465]
Dec 2020 – Jul 2021, Indonesia (phase I), United States (phase I/II)
Takis Biotech
Italy DNA Phase I–II (160)[466]
Phase I:First-in-human, dose escalation.
Phase II: Open-label, randomize, dose expansion.
Feb–Sep 2021, Italy
Chulalongkorn University
Thailand RNA Phase I–II (96)[467]
Dose-finding Study.
Jan–Mar 2021, Thailand
Shenzhen Genoimmune Medical Institute[468]
China Lentiviral vector (with minigene modifying aAPCs) Phase I (100)
Mar 2020 – Jul 2023, Shenzhen
Shenzhen Genoimmune Medical Institute[468]
China Lentiviral vector (with minigene modifying DCs) Phase I (100)
Mar 2020 – Jul 2023, Shenzhen
ImmunityBio COVID-19 vaccine (hAd5)
United States Viral vector Phase I–II (540)[469][470][471][472][473]
Phase 1/2 Study of the Safety, Reactogenicity, and Immunogenicity of a Subcutaneously- and Orally- Administered Supplemental Spike & Nucleocapsid-targeted COVID-19 Vaccine to Enhance T Cell Based Immunogenicity in Participants Who Have Already Received Prime + Boost Vaccines Authorized For Emergency Use.
Oct 2020  – Sep 2021, South Africa, United States
Gennova Biopharmaceuticals, HDT Biotech Corporation[475]
India, United States RNA Phase I–II (620)[476][477]
Phase I (120)
Phase II (500)
Jan 2021 – ?, India
Bangavax (Bancovid)[478][479]
Globe Biotech Ltd. of Bangladesh
Bangladesh RNA Preclinical
Awaiting for approval from Bangladesh government to conduct the first clinical trial.[480]
Providence Therapeutics
Canada RNA Phase I (60)[481]
First-in-Human, Observer-Blinded, Randomized, Placebo Controlled.[482]
Jan–May 2021, Canada
VIDO (University of Saskatchewan)
Canada Subunit Phase I (108)[483]
Randomized, observer-blind, dose-escalation.[484]
Feb 2021 – Oct 2022, Halifax
COVI-VAC (CDX-005)[485]
Codagenix Inc.
United States Attenuated Phase I (48)[486]
First-in-human, randomised, double-blind, placebo-controlled, dose-escalation
Dec 2020 – Jun 2021, United Kingdom
United Kingdom RNA Phase I (40)[487]
Open-label, dose escalation, non-randomized
Feb–Jun 2021, United States
University of Sydney
Australia DNA Phase I (150)[488]
Double-blind, dose-ranging, randomised, placebo-controlled.
Feb 2021 – Jun 2022, Sydney
Bharat Biotech[490]
India Adenovirus vector (intranasal) Phase I (175)[489]
Randomized, double-blinded, multicenter.
Mar 2021, India
Meissa Vaccine Inc.
United States Attenuated Phase I (130)[492]
Randomized, double-blinded, multicenter.
Mar 2021 – Oct 2022, United States
Japan Subunit Phase I–II (214)[493]
Randomized, double-blind, placebo-controlled, parallel-group.
Dec 2020 – Jun 2022, Japan
SK Bioscience Co. Ltd.
South Korea Subunit Phase I–II (580)[494][495]
Phase I-II (260-320): Placebo-controlled, randomized, observer-blinded, dose-finding.
Jan–Aug 2021, South Korea
Kentucky Bioprocessing
United States Subunit Phase I–II (180)[496]
First-in-human, observer-blinded, randomized, placebo-controlled, parallel group
Dec 2020 – May 2021, United States
Cellid Co
South Korea Viral vector Phase I–II (150)[497]
Phase I: Dose Escalation, Single Center, Open.
Phase IIa: Multicenter, Randomized, Open.
Dec 2020 – Mar 2021, South Korea
Adimmune Corporation
Taiwan Subunit Phase I (70)[498]
Randomized, single center, open-label, dose-finding.
Aug–Nov 2020, Taiwan
University Medical Center Groningen
Netherlands Subunit Phase I–II (130)[499]
Non-randomized, Single-center, open-label, combinatorial.
Apr–Jun 2021, Netherlands
GeneOne Life Science Inc.
South Korea DNA Phase I–II (345)[500]
Multicenter, Randomized, Combined Phase I Dose-escalation and Phase IIa Double-blind.
Dec 2020 – Jul 2022, South Korea
Covigenix VAX-001
Entos Pharmaceuticals Inc.
Canada DNA Phase I–II (72)[501]
Placebo-controlled, randomized, observer-blind, dose ranging adaptive.
Mar–Aug 2021, Canada
City of Hope Medical Center
United States Viral vector Phase I (129)[502]
Dose Escalation Study.
Dec 2020 – Nov 2022, California
SK Bioscience Co. Ltd.
South Korea DNA Phase I (50)[503]
Placebo-controlled, Randomized, Observer-blinded, Dose-escalation.
Dec 2020 – Apr 2021, South Korea
University of Tübingen
Germany Subunit Phase I (36)[504]
Placebo-controlled, Randomized, Observer-blinded, Dose-escalation.
Nov 2020 – Sep 2021, Germany
Canada DNA Phase I (24)[505]
Randomized, observer-blind, placebo-controlled.
Nov 2020 – Feb 2022, Australia
Providence Health & Services
United States DNA Phase I (36)[506]
Dec 2020 – May 2021, United States
NIAID, Gritstone Oncology
United States Viral vector Phase I (130)[507]
Open-label, dose and age escalation, parallel design.
Mar 2021 – Sep 2022, United States
Altimmune Inc.
United States Viral vector Phase I (180)[508]
Double-blind, randomized, placebo-controlled, first-in-Human.
Feb 2021 – Feb 2022, United States
United States Viral vector Phase I (35)[509]
Double-blind, randomized, placebo-controlled, first-in-Human.
Sep 2020 – May 2021, United States
SpFN COVID-19 vaccine
United States Army Medical Research and Development Command
United States Subunit Phase I (72)[510]
Randomized, double-blind, placebo-controlled.
Apr 2021 – Oct 2022, United States
University Medical Center Hamburg-Eppendorf
Germany Viral vector Phase I–II (270)[511][512]
Phase I (30): Open, Single-center.
Phase Ib/IIa (240): Multi-center, Randomized Controlled.
Oct 2020 – Mar 2022, Germany
Jiangsu Rec-Biotechnology Co Ltd
China Subunit Phase I (160)[513]
First-in-human, randomized, double-blind, placebo-controlled, dose-finding.
Apr–Jul 2021, New Zealand
SARS-CoV-2 VLP vaccine
Ihsan Gursel, Scientific and Technological Research Council of Turkey
Turkey Virus-like particle Phase I (36)[514]
double-blinded, randomised, placebo controlled.
Mar 2021 – Jan 2022, Turkey
Koçak-19 Inaktif Adjuvanlı COVID-19 vaccine
Kocak Farma
Turkey Inactivated SARS‑CoV‑2 Phase I (38)[515]
Phase 1 Study for the Determination of Safety and Immunogenicity of Different Strengths of Koçak-19 Inaktif Adjuvanlı COVID-19 Vaccine, Given Twice Intramuscularly to Healthy Volunteers, in a Placebo Controlled Study Design.
Mar–Jun 2021, Turkey
United States RNA Phase I (125)[516]
Randomized, observer-blind, dose-ranging study.
Mar 2021 – Apr 2022, United States
Daiichi Sankyo[518]
Japan RNA Phase I–II (152)[519]
A Phase 1/2 Study to Assess the Safety, Immunogenicity and Recommended Dose of DS-5670a (COVID-19 Vaccine) in Japanese Healthy Adults and Elderly Subjects.
Mar 2021 – Jul 2022, Japan
Syneos Health, US Specialty Formulations
United States Subunit Phase I (45)[520]
Jun–Dec 2021, New Zealand
KM Biologics Co
Japan Inactivated SARS‑CoV‑2 Phase I–II (210)[521]
Randomized, double blind, placebo control, parallel group.[522]
Mar 2021 – Dec 2022, Japan
OSE Immunotherapeutics
France Subunit Phase I (48)[523][524]
Randomized, open label.
Apr–Sept 2021, France
Bavarian Nordic.[525] Radboud University Nijmegen
Denmark, Netherlands Virus-like particle Phase I (42)[526]
Single center, sequential dose-escalation, open labelled trial.
Mar–Dec 2021, Netherlands
Senai Cimatec
Brazil RNA Phase I (78)[527]
Randomized, open-label, dose-escalation.
May–Sep 2021, Brazil
Tetherex Pharmaceuticals
United States Viral vector Phase I (40)[528]
First-In-Human, Open-label, Single Ascending Dose and Multidose.
Jun–Dec 2021, Australia
Osman ERGANIS, Scientific and Technological Research Council of Turkey
Turkey Inactivated SARS‑CoV‑2 Phase I (50)[529]
Phase I Study Evaluating the Safety and Efficacy of the Protective Adjuvanted Inactivated Vaccine Developed Against SARS-CoV-2 in Healthy Participants, Administered as Two Injections Subcutaneously in Two Different Dosages.
Apr–Oct 2021, Turkey
Elixirgen Therapeutics, Fujita Health University
Japan, United States RNA Phase I–II (60)[530]
First in Human, randomized, placebo-controlled.
Apr 2021 – Jan 2023, Japan
Laboratorio Avimex, National Council of Science and Technology
Mexico Viral vector Phase I (90)[532]
Dose-escalation, open-label, non-randomized.
Apr–Aug 2021, Mexico
mRNACOVID-19 Vaccine
Stemirna Therapeutics Co. Ltd.
China RNA Phase I (240)[533]
Randomized, double-blind, placebo-controlled.
Mar–Jul 2021, China
Icosavax, Seqirus Inc.
United States Virus-like particle Phase I–II (168)[534][535]
Randomized, observer-blinded, placebo-controlled.
Jun 2021–2022, Australia
China Subunit Preclinical
Awaited for the conduct on Phase I/II trials.[536]
Vabiotech COVID-19 vaccine
Vaccine and Biological Production Company No. 1 (Vabiotech)
Vietnam Subunit Preclinical
Awaited for the conduct on Phase I trial.[537]
United States DNA Preclinical
Awaited for the conduct on Phase I/II trials.[538]
North's Academy of Medical Science Medical biology institute
North Korea Subunit (spike protein with Angiotensin-converting enzyme 2) Phase I–II (?)[539]
Jul 2020, North Korea
MRC clinical trials unit at Imperial College London
United Kingdom RNA Terminated (105)
Randomized trial, with dose escalation study (15) and expanded safety study (at least 200)
Jun 2020 – Jul 2021, United Kingdom
Institut Pasteur
France Viral vector Terminated (90)[541]
Randomized, Placebo-controlled.
Aug 2020 – Jun 2021, Belgium, France
SARS-CoV-2 Sclamp/V451[125][126]
UQ, Syneos Health, CEPI, Seqirus
Australia Subunit (molecular clamp stabilized spike protein with MF59) Terminated (120)
Randomised, double-blind, placebo-controlled, dose-ranging.
False positive HIV test found among participants.
Jul–Oct 2020, Brisbane
V590[542] and V591/MV-SARS-CoV-2[543] Merck & Co. (Themis BIOscience), Institut Pasteur, University of Pittsburgh's Center for Vaccine Research (CVR), CEPI United States, France Vesicular stomatitis virus vector[544] / Measles virus vector[545] Terminated
In phase I, immune responses were inferior to those seen following natural infection and those reported for other SARS-CoV-2/COVID-19 vaccines.[546]
  1. ^ Serum Institute of India will be producing the ChAdOx1 nCoV-19 vaccine for India[218] and other low- and middle-income countries.[219]
  2. ^ Oxford name: ChAdOx1 nCoV-19. Manufacturing in Brazil to be carried out by Oswaldo Cruz Foundation.[220]
  3. ^ a b Recommended interval. The second dose of the Pfizer–BioNTech and Moderna vaccines can be administered up to six weeks after the first dose to alleviate a shortage of supplies.[228][229]
  4. ^ Long-term storage temperature. The Pfizer–BioNTech COVID-19 vaccine can be kept between −25 and −15 °C (−13 and 5 °F) for up to two weeks before use, and between 2 and 8 °C (36 and 46 °F) for up to five days before use.[230][231]
  5. ^ Storage temperature for the frozen Gam-COVID-Vac formulation. The lyophilised Gam-COVID-Vac-Lyo formulation can be stored at 2-8°C.[238]
  6. ^ Latest Phase with published results.
  7. ^ Virus-like particles grown in Nicotiana benthamiana[359]
  8. ^ Phase I–IIa in South Korea in parallel with Phase II–III in the US


As of September 2020, eleven of the vaccine candidates in clinical development use adjuvants to enhance immunogenicity.[27] An immunological adjuvant is a substance formulated with a vaccine to elevate the immune response to an antigen, such as the COVID‑19 virus or influenza virus.[547] Specifically, an adjuvant may be used in formulating a COVID‑19 vaccine candidate to boost its immunogenicity and efficacy to reduce or prevent COVID‑19 infection in vaccinated individuals.[547][548] Adjuvants used in COVID‑19 vaccine formulation may be particularly effective for technologies using the inactivated COVID‑19 virus and recombinant protein-based or vector-based vaccines.[548] Aluminum salts, known as "alum", were the first adjuvant used for licensed vaccines, and are the adjuvant of choice in some 80% of adjuvanted vaccines.[548] The alum adjuvant initiates diverse molecular and cellular mechanisms to enhance immunogenicity, including release of proinflammatory cytokines.[547][548]


Location Vaccinated[b] % of pop.[c]
  World[d] 1,632,389,656 20.9%
 China[e] 923,910,000 --
 United States 174,674,144 52.2%
 EU 199,108,492 44.8%
 India 207,830,971 15.1%
 Brazil 56,479,200 26.6%
 United Kingdom 41,831,056 61.6%
 Germany 40,475,199 48.3%
 France 30,374,473 45.0%
 Italy 29,949,601 49.5%
 Mexico 26,422,800 20.5%
 Turkey 23,227,162 27.7%
 Spain 21,713,840 46.4%
 Russia 18,550,270 12.7%
 Indonesia 20,904,723 7.6%
 Canada 24,683,269 65.4%
 Japan 19,262,621 15.2%
 Poland 15,549,895 41.1%
 South Korea 13,219,207 25.5%
 Chile 11,744,468 61.4%
 Morocco 9,368,046 25.4%
 Argentina 13,223,188 29.3%
 Saudi Arabia[e] 16,109,908 --
 United Arab Emirates[e] 13,964,439 --
 Colombia 9,291,221 18.3%
 Netherlands 7,759,667 45.3%
 Pakistan 8,908,051 4.0%
 Israel 5,485,236 63.4%
 Bangladesh 5,823,245 3.5%
 Hungary 5,311,475 55.0%
 Belgium 5,712,486 49.3%
 Romania 4,567,268 23.7%
 Greece 4,302,109 41.3%
 Portugal 4,574,997 44.9%
 Philippines 5,068,855 4.6%
 Thailand 4,948,227 7.1%
 Czech Republic 4,610,875 43.1%
 Sweden 4,201,394 41.6%
 Austria 4,279,537 47.5%
 Dominican Republic 4,272,574 39.4%
 Switzerland 3,752,011 43.4%
 Australia 5,232,353 20.5%
 Cambodia 3,076,775 18.4%
 Peru 3,567,962 10.8%
 Serbia 2,656,065 39.0%
 Malaysia 3,435,420 10.6%
 Iran 3,984,095 4.7%
 Singapore 2,700,446 46.2%
 Denmark 2,777,818 48.0%
 Kazakhstan 2,547,363 13.6%
 Cuba 2,005,691 17.7%
 Egypt 2,997,129 2.9%
 Finland 2,848,931 51.4%
 Mongolia 1,897,956 57.9%
 Uruguay 2,109,379 60.7%
 Norway 1,975,770 36.4%
 Nepal 2,438,127 8.4%
 Slovakia 1,913,557 35.0%
 Ireland[e] 3,100,000 --
 Ecuador 2,043,159 11.6%
 Hong Kong 1,790,659 23.9%
 Myanmar 1,772,177 3.3%
 Sri Lanka 2,317,012 10.8%
 Kuwait 2,875,000 67.3%
 Qatar 1,601,801 55.6%
 Azerbaijan 1,842,954 18.2%
 Jordan 1,969,242 19.3%
 Algeria 2,500,000 5.7%
 El Salvador 1,384,489 21.4%
 Nigeria 1,964,095 0.9%
 Croatia 1,419,924 34.6%
 Costa Rica 1,409,778 27.7%
 Uzbekistan[e] 2,136,423 --
 Bolivia 1,572,351 13.5%
 Lithuania 1,183,917 43.5%
 Ethiopia[e] 1,948,073 --
 Bahrain 1,032,832 60.7%
 South Africa[e] 1,871,987 --
 Ukraine 1,543,263 3.5%
 Vietnam 1,584,436 1.6%
 Bulgaria 888,892 12.8%
 Tunisia 1,032,192 8.7%
 Slovenia 778,235 37.4%
 Panama 891,151 20.6%
 Angola 822,109 2.5%
 Ghana 852,047 2.7%
 Laos 717,648 9.9%
 Kenya 987,277 1.8%
 Zimbabwe 693,568 4.7%
 Lebanon 716,565 10.5%
 Taiwan 1,009,160 4.2%
 Latvia 574,168 30.4%
 Belarus 610,988 6.5%
 New Zealand 567,188 11.8%
 Estonia 530,511 40.0%
 Albania 507,764 17.6%
 Uganda 803,797 1.8%
 Venezuela 588,066 2.1%
 Cyprus 436,280 49.8%
 Ivory Coast 705,051 2.7%
 Iraq 494,524 1.2%
 Guatemala 547,657 3.1%
 Afghanistan 484,737 1.2%
 Palestine 408,803 8.0%
 Senegal 480,311 2.9%
 Oman 435,090 8.5%
 Malta 341,941 77.4%
 Moldova 388,808 9.6%
 Sudan 453,690 1.0%
 Maldives 314,194 58.1%
 Bhutan 482,716 62.6%
 Honduras 421,925 4.3%
 Mauritius 247,673 19.5%
 North Macedonia 259,395 12.4%
 Luxembourg 270,860 43.3%
 Paraguay 315,186 4.4%
 Guinea 304,716 2.3%
 Rwanda 350,400 2.7%
 Mozambique 320,129 1.0%
 Malawi 373,577 1.9%
 Togo 270,784 3.3%
 Libya 330,260 4.8%
 Iceland 224,191 65.7%
 Bosnia and Herzegovina 252,499 7.7%
 Guyana 216,862 27.6%
 Georgia 212,163 5.3%
 Montenegro 145,636 23.2%
 Macau 181,797 28.0%
 Equatorial Guinea 148,579 10.6%
 Fiji 237,940 26.5%
 Yemen 221,380 0.7%
 Jamaica 163,209 5.5%
 Niger 172,812 0.7%
 Trinidad and Tobago 167,027 11.9%
 Nicaragua 167,500 2.5%
 Mali 121,077 0.6%
 Curaçao 87,525 53.3%
 Somalia 135,107 0.8%
 Barbados 88,373 30.8%
 Madagascar 150,329 0.5%
 Botswana 150,019 6.4%
 Zambia 141,829 0.8%
 Suriname 119,956 20.4%
 Seychelles 70,653 71.8%
 Kyrgyzstan 88,178 1.4%
 Northern Cyprus 75,463 19.7%
 Aruba 66,336 62.1%
 French Polynesia 64,749 23.1%
 Jersey 64,541 63.9%
 Namibia 88,649 3.5%
 New Caledonia 55,277 19.4%
 Kosovo 98,277 5.1%
 Tajikistan 83,743 0.9%
 East Timor 93,152 7.1%
 Sierra Leone 77,958 1.0%
 Isle of Man 62,400 73.4%
 Cameroon 72,111 0.3%
 Belize 72,453 18.2%
 Cayman Islands 46,928 71.4%
 Comoros 43,140 5.0%
 Gibraltar 39,133 116.2%
 Bermuda 41,198 66.2%
 Guernsey[e] 75,181 --
 Syria 71,519 0.4%
 Bahamas 50,292 12.8%
 Liberia 66,884 1.3%
 Brunei 51,908 11.9%
 Congo[e] 62,231 --
 Antigua and Barbuda 34,883 35.6%
 Saint Lucia 29,655 16.1%
 Mauritania 42,333 0.9%
 Cape Verde 45,013 8.1%
 Armenia 46,503 1.6%
 San Marino[e] 43,651 --
 Central African Republic 41,095 0.8%
 Turkmenistan 32,240 0.5%
 Andorra 30,535 39.5%
 Gambia 30,421 1.3%
 Faroe Islands 25,686 52.6%
 Samoa 40,230 20.3%
 Papua New Guinea 38,176 0.4%
 Dominica 20,048 27.9%
 DR Congo 34,330 0.0%
 Lesotho 36,637 1.7%
 Turks and Caicos Islands 20,760 53.6%
 Eswatini 35,227 3.0%
 Sint Maarten 19,541 45.6%
 Monaco 18,836 48.0%
 Gabon 23,260 1.1%
 Saint Kitts and Nevis 21,469 40.4%
 Greenland 21,179 37.3%
 Tonga 28,631 27.1%
 Grenada 18,415 16.4%
 Liechtenstein 16,479 43.2%
 Benin 21,834 0.2%
 São Tomé and Príncipe 12,374 5.7%
 Saint Vincent and the Grenadines[e] 22,746 --
 Djibouti 12,547 1.3%
 British Virgin Islands 12,245 40.5%
 South Sudan 17,350 0.1%
 Guinea-Bissau 18,706 0.9%
 Burkina Faso 17,775 0.1%
 Solomon Islands 17,000 2.5%
 Anguilla 9,119 60.8%
 Cook Islands 9,589 54.6%
 Wallis and Futuna 4,470 39.8%
 Saint Helena 4,361 71.8%
 Nauru 7,438 68.7%
 Caribbean Netherlands 5,726 21.8%
 Chad 5,324 0.0%
 Vanuatu 5,140 1.7%
 Tuvalu 4,772 40.5%
 Falkland Islands 2,632 75.6%
 Montserrat 1,389 27.8%
 Micronesia[f][550] 27,356 26.4%
 Marshall Islands[f][550] 17,080 29.2%
 Palau[f][550] 13,808 77.1%
 Vatican City[g][551] 10,494 1,297.2%



  1. ^ Latest available data as of this date. Individual country reporting frequency varies.
  2. ^ Number of unique individuals who have received at least one dose of a COVID-19 vaccine (unless noted otherwise).
  3. ^ Includes those who are partially vaccinated with a single dose. May include vaccination of non-citizens, which can push totals beyond 100% of the local population.
  4. ^ Some countries are not yet reporting first-dose counts. Total dose counts for these countries are not included in the World total.
  5. ^ a b c d e f g h i j k This country's data reflects total doses administered, not the first shot only.
  6. ^ a b c This country, a Freely Associated State, has its data included in the United States' totals.
  7. ^ The data is included in Italy's totals.

As of 15 June 2021, 2.40 billion COVID-19 vaccine doses had been administered worldwide based on official reports from national health agencies collated by Our World in Data.[552]

During a pandemic on the rapid timeline and scale of COVID-19 cases during 2020, international organizations like the World Health Organization (WHO) and Coalition for Epidemic Preparedness Innovations (CEPI), vaccine developers, governments, and industry are evaluating the distribution of the eventual vaccine(s).[553] Individual countries producing a vaccine may be persuaded to favor the highest bidder for manufacturing or provide first-service to their own country.[554][555][556][557] Experts emphasize that licensed vaccines should be available and affordable for people at the frontline of healthcare and having the greatest need.[554][555][557] In April 2020, it was reported that the UK agreed to work with 20 other countries and global organizations including France, Germany and Italy to find a vaccine and to share the results and that UK citizens would not get preferential access to any new COVID‑19 vaccines developed by taxpayer-funded UK universities.[558] Several companies plan to initially manufacture a vaccine at artificially low pricing, then increase prices for profitability later if annual vaccinations are needed and as countries build stock for future needs.[557]

An April 2020 CEPI report stated: "Strong international coordination and cooperation between vaccine developers, regulators, policymakers, funders, public health bodies, and governments will be needed to ensure that promising late-stage vaccine candidates can be manufactured in sufficient quantities and equitably supplied to all affected areas, particularly low-resource regions."[559] The WHO and CEPI are developing financial resources and guidelines for global deployment of several safe, effective COVID‑19 vaccines, recognizing the need is different across countries and population segments.[553][560][561][562] For example, successful COVID‑19 vaccines would likely be allocated first to healthcare personnel and populations at greatest risk of severe illness and death from COVID‑19 infection, such as the elderly or densely-populated impoverished people.[563][564]

The WHO, CEPI, and GAVI have expressed concerns that affluent countries should not receive priority access to the global supply of eventual COVID‑19 vaccines, but rather protecting healthcare personnel and people at high risk of infection are needed to address public health concerns and reduce economic impact of the pandemic.[559][561][563] WHO Director General Tedros Adhanom referred to subsequent inequities in the distribution as "a catastrophic moral failure".[565] A March 2021 survey of 77 epidemiologists concluded that mutations would render existing vaccines ineffective within one year — a window which wealthy nations were on pace to meet.[566] Conversely, an Economist Intelligence Unit report from earlier in the year estimated that a similar level of herd immunity would not be achieved globally until 2024.[565]

Inequity concerns

In a meeting in April 2021, the World Health Organization's emergency committee addressed concerns of persistent inequity in the global vaccine distribution.[567] Although 9 percent of the world's population lives in the 29 poorest countries, these countries received only 0.3% of all vaccines administered as of May 2021.[568] Locally, in a Agência Pública article from March 15, 2021, Brazil vaccinated twice more white than black people and noticed the fact that the mortality of COVID-19 is bigger in the black population.[569]


On 4 February 2020, US Secretary of Health and Human Services Alex Azar published a notice of declaration under the Public Readiness and Emergency Preparedness Act for medical countermeasures against COVID‑19, covering "any vaccine, used to treat, diagnose, cure, prevent, or mitigate COVID‑19, or the transmission of SARS-CoV-2 or a virus mutating therefrom", and stating that the declaration precludes "liability claims alleging negligence by a manufacturer in creating a vaccine, or negligence by a health care provider in prescribing the wrong dose, absent willful misconduct".[570] The declaration is effective in the United States through 1 October 2024.[570]

In December 2020, the UK government granted Pfizer legal indemnity for its COVID-19 vaccine.[571]

In the European Union, the COVID‑19 vaccines are licensed under a Conditional Marketing Authorisation which does not exempt manufacturers from civil and administrative liability claims.[572] While the purchasing contracts with vaccine manufacturers remain secret, they do not contain liability exemptions even for side-effects not known at the time of licensure.[573]

The Bureau of Investigative Journalism, a nonprofit news organization, reported in an investigation that unnamed officials in some countries, such as Argentina and Brazil, said that Pfizer demanded guarantees against costs of legal cases due to adverse effects in the form of liability waivers and sovereign assets such as federal bank reserves, embassy buildings or military bases, going beyond the expected from other countries such as the US.[574] During the pandemic parliamentary inquiry in Brazil, Pfizer's representative said that its terms for Brazil are the same as for all other countries with which it has signed deals.[575]

Preventive measures after vaccination

While vaccines substantially reduce the probability of infection, it is still possible for fully vaccinated people to contract and spread COVID-19.[167] Public health agencies have recommended that vaccinated people continue using preventive measures (wear face masks, social distance, wash hands) to avoid infecting others, especially vulnerable people, particularly in areas with high community spread. Governments have indicated that such recommendations will be reduced as vaccination rates increase and community spread declines.[576]

Society and culture


Nations pledged to buy doses of COVID‑19 vaccine before the doses were available. Though high-income nations represent only 14% of the global population, as of 15 November 2020, they had contracted to buy 51% of all pre-sold doses. Some high-income nations bought more doses than would be necessary to vaccinate their entire populations.[13]

Elderly receiving second dose of CoronaVac vaccine in Brazil.

On 18 January 2021, WHO Director-General Tedros Adhanom Ghebreyesus warned of problems with equitable distribution: "More than 39 million doses of vaccine have now been administered in at least 49 higher-income countries. Just 25 doses have been given in one lowest-income country. Not 25 million; not 25 thousand; just 25."[577]

Production of Sputnik V vaccine in Brazil

In March, it was revealed the US attempted to convince Brazil not to purchase the Sputnik V COVID-19 vaccine, fearing "Russian influence" in Latin America.[578] Some nations involved in long-standing territorial disputes have reportedly had their access to vaccines blocked by competing nations; Palestine has accused Israel blocking vaccine delivery to Gaza, while Taiwan has suggested that China has hampered its efforts to procure vaccine doses.[579][580][581]

A single dose of the COVID‑19 vaccine by AstraZeneca would cost 47 Egyptian pounds (EGP) and the authorities are selling it between 100 and 200 EGP. A report by Carnegie Endowment for International Peace cited the current poverty rate in Egypt as around 29.7 percent, which constitutes approximately 30.5 million people, and claimed that about 15 million of the Egyptians would be unable to gain access to the luxury of vaccination. A human rights lawyer, Khaled Ali launched a lawsuit against the government, forcing them to provide vaccination free of cost to all members of the public.[582]

According to immunologist Dr. Anthony Fauci, mutant strains of virus and limited vaccine distribution pose continuing risks and he said: "we have to get the entire world vaccinated, not just our own country."[583] Edward Bergmark and Arick Wierson are calling for an global vaccination effort and wrote that the wealthier nations' "me-first" mentality could ultimately backfire, because the spread of the virus in poorer countries would lead to more variants, against which current vaccines could be less effective.[584]

On 10 March 2021, the United States, Britain, European Union nations and other WTO members, blocked a push by more than eighty developing countries to waive COVID‑19 vaccine patent rights in an effort to boost production of vaccines for poor nations.[585] On 5 May 2021, the Biden administration announced that it supports waiving intellectual property protections for COVID-19 vaccines.[586] The Members of the European Parliament have backed a motion demanding the temporary lifting of intellectual properties rights for Covid-19 vaccines.[587] Commission Vice-President Valdis Dombrovskis, stressed that while the EU is ready to discuss the issue of patent waivers, its proposed solutions include limiting export restrictions, resolving production bottlenecks, looking into compulsory licensing, investing in manufacturing capacity in developing countries and increasing contributions to the COVAX scheme.[588]

In May 2021, UNICEF made an urgent appeal to industrialised nations to pool their excess COVID-19 vaccine capacity to make up for a 125-million-dose gap in the COVAX program. The program mostly relied on the Oxford–AstraZeneca COVID-19 vaccine produced by SRI, which faced serious supply problems due to increased domestic vaccine needs in India from March to June 2021. Currently, only a limited amount of vaccines can be distributed efficiently, and the shortfall of vaccines in South America and parts of Asia are due to a lack of expedient donations by richer nations. International aid organisations have pointed at Nepal, Sri Lanka, and Maldives as well as Argentina and Brazil, and some parts of the Caribbean as problem areas, where vaccines are in short supply. UNICEF has also been critical towards proposed donations of Moderna and Pfizer vaccines since these are not slated for delivery until the second half of 2021, or early 2022.[589]


Anti-vaccination activists and other people spread a variety of rumors, including overblown claims about side effects, a story about COVID-19 being spread by childhood vaccines, misrepresentations about how the immune system works, and when and how COVID-19 vaccines are made.

Vaccine hesitancy

Some 10% of the public perceives vaccines as unsafe or unnecessary, refusing vaccination – a global health threat called vaccine hesitancy[590] – which increases the risk of further viral spread that could lead to COVID‑19 outbreaks.[41] As of May 2020, estimates from two surveys were that 67% or 80% of people in the U.S. would accept a new vaccination against COVID‑19, with wide disparity by education level, employment status, ethnicity, and geography.[591] In March 2021, 19% of US adults claimed to have been vaccinated while 50% announced plans to get vaccinated.[592][593]

In an effort to demonstrate the vaccine's safety, prominent politicians have received it on camera, with others pledging to do so.[594][595][596]

Encouragement by public figures and celebrities

Many public figures and celebrities have publicly declared that they have been vaccinated against COVID‑19, and encouraged people to get vaccinated. Many have made video recordings or otherwise documented their vaccination. They do this partly to counteract vaccine hesitancy and COVID‑19 vaccine conspiracy theories.[597]

Politicians and heads of state

Peru's interim President Francisco Sagasti gets vaccinated against COVID-19 at a military hospital in Lima

Several current and former heads of state and government ministers have released photographs of their vaccinations, encouraging others to be vaccinated, including Kyriakos Mitsotakis, Zdravko Marić, Olivier Véran, Joe Biden, Barack Obama, George W. Bush, Bill Clinton, the Dalai Lama, Narendra Modi, Justin Trudeau, Alexandria Ocasio-Cortez, Nancy Pelosi and Kamala Harris.[598][599]

Elizabeth II and Prince Philip announced they had the vaccine, breaking from protocol of keeping the British royal family's health private.[597] Pope Francis and Pope Emeritus Benedict both announced they had been vaccinated.[597]


Dolly Parton recorded herself getting vaccinated with the Moderna vaccine she helped fund, she encouraged people to get vaccinated and created a new version of her song "Jolene" called "Vaccine".[597] Patti Smith, Yo-Yo Ma, Carole King, Tony Bennett, Mavis Staples, Brian Wilson, Joel Grey, Loretta Lynn, Willie Nelson, and Paul Stanley have all released photographs of them being vaccinated and encouraged others to do so.[598] Grey stated "I got the vaccine because I want to be safe. We've lost so many people to COVID. I've lost a few friends. It's heartbreaking. Frightening."[598]

Actresses and actors

Amy Schumer, Rosario Dawson, Arsenio Hall, Danny Trejo, Mandy Patinkin, Samuel L. Jackson, Arnold Schwarzenegger, Sharon Stone, Kate Mulgrew, Jeff Goldblum, Jane Fonda, Anthony Hopkins, Bette Midler, Kim Cattrall, Isabella Rossellini, Christie Brinkley, Cameran Eubanks, Hugh Bonneville, Alan Alda, David Harbour, Sean Penn, Amanda Kloots, Ian McKellen and Patrick Stewart have released photographs of themselves getting vaccinated and encouraging others to do the same.[597][598] Dame Judi Dench and Joan Collins announced they have been vaccinated.[597]

TV personalities

Martha Stewart, Jonathan Van Ness, Al Roker and Dan Rather released photographs of themselves getting vaccinated and encouraged others to do the same.[597][598] Stephen Fry also shared a photograph of being vaccinated; he wrote, "It's a wonderful moment, but you feel that it's not only helpful for your own health, but you know that you're likely to be less contagious if you yourself happen to carry it ... It's a symbol of being part of society, part of the group that we all want to protect each other and get this thing over and done with."[597] Sir David Attenborough announced that he has been vaccinated.[597]


Magic Johnson and Kareem Abdul-Jabbar released photographs of themselves getting vaccinated and encouraged others to do the same; Abdul-Jabbar said, "We have to find new ways to keep each other safe."[598]

Specific communities

Romesh Ranganathan, Meera Syal, Adil Ray, Sadiq Khan and others produced a video specifically encouraging ethnic minority communities in the UK to be vaccinated including addressing conspiracy theories stating "there is no scientific evidence to suggest it will work differently on people from ethnic minorities and that it does not include pork or any material of fetal or animal origin."[600]

Oprah Winfrey and Whoopi Goldberg have spoken about being vaccinated and encouraged other black Americans to be so.[598] Stephanie Elam volunteered to be a trial volunteer stating "a large part of the reason why I wanted to volunteer for this COVID‑19 vaccine research – more Black people and more people of color need to be part of these trials so more diverse populations can reap the benefits of this medical research."[598]

See also


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