Here’s the latest on COVID-19 vaccines

These are the COVID-19 vaccine prospects that have made it to phase three trials and beyond.

    • U.S. President Joe Biden announced that Johnson & Johnson has reached a deal with pharmaceutical company Merck to help produce its COVID-19 vaccine, a partnership that could potentially double the supply of doses.
    • Given the increased supply, Biden said the U.S. will now have enough doses to vaccinate all adults in the country by the end of May rather than the end of July, as previously estimated. 

COVID-19 vaccines have reached consumers in record time. Though the process can typically take 10 to 15 years, the U.S. Food and Drug Administration has granted emergency authorization to vaccines made by Pfizer, Moderna, and Johnson & Johnson in less than a year. Before now, the fastest-ever vaccine—for mumps—took four years to develop in the 1960s.

Even after a vaccine is authorized or fully licensed, it faces potential roadblocks when it comes to scaling up production and distribution, which also includes deciding which populations should get it first—and at what cost. CDC director Robert Redfield, vaccine developers, and the FDA have said it’s unlikely COVID-19 vaccines will be widely available until the middle of 2021. (Here's why determining who is “first in line” for the vaccine depends on your state.)

Yet several efforts are underway to help produce and distribute the vaccines more quickly. Here’s everything you need to know—including primers on how vaccines and clinical trials work, the latest news on vaccine distribution and safety, and a detailed breakdown of each of the candidates that have reached phase three and beyond.

Vaccines and clinical trials

More than 60 vaccines are still going through a three-stage clinical trial process that’s required before they are sent to regulatory agencies for approval. Given the urgent need, some vaccine developers have compressed the clinical process for SARS-CoV-2 by running trial phases simultaneously.

The COVID-19 candidates, like all vaccines, essentially aim to instruct the immune system to mount a defense, which is sometimes stronger than what would be provided through natural infection and comes with fewer health consequences.

To do so, traditional vaccines use the whole coronavirus, but in a killed or weakened state. Others use only part of the virus—whether a protein or a fragment. Some transfer the instructions for coronavirus proteins into an unrelated virus that is unlikely or even incapable of causing disease. Finally, cutting-edge vaccines under development rely on deploying pieces of the coronavirus’s genetic material, enabling our cells to temporarily make coronavirus proteins needed to stimulate our immune systems. (Find out more about vaccines and how they work.)

Vaccine rollout and safety

On February 27, the FDA granted emergency use authorization for the single-dose vaccine made by Johnson & Johnson's Janssen Biotech, Inc. The company has pledged to provide 100 million doses within the first half of 2021. That tally adds to the 200 million additional doses of the Moderna and Pfizer-BioNTech vaccines the Biden administration secured on February 11. The total amount means the country has enough vaccine doses to immunize every American adult by the end of May. The Biden administration also plans to deliver more doses directly to drugstores and pharmacies to speed up delivery as part of the $1.9 trillion COVID-19 rescue plan the administration released in January.

States are still responsible for rollout decision-making, which has caused confusion and uncertainty as the states differed in their vaccine priorities. But most states have now expanded eligibility to frontline workers and people age 65 and older. Pediatrician and former U.S. Food and Drug Administration head David Kessler is leading the U.S. plan to accelerate the development and rollout of vaccines for COVID-19. Biden’s plan calls for launching community vaccination centers and deploying mobile vaccination units to hard-to-reach areas, as well as free vaccines for all people in the U.S. regardless of immigration status. 

The World Health Organization is also coordinating global efforts to develop a vaccine, with an eye toward delivering two billion doses by the end of 2021. On February 19, the Biden administration said it will pledge $4 billion to the COVAX Facility, the WHO-led initiative to ensure that all countries have equitable access to the vaccine. It will donate $2 billion immediately and dispense the rest over the next two years. The program delivered its first shipment of vaccine on February 24, with the arrival of 600,000 doses in Accra, Ghana. The WHO has approved the Pfizer-BioNTech and AstraZeneca-Oxford vaccines for emergency use and is reportedly in late stages of reviewing the candidates from Moderna, Sinopharm, and Sinovac.

As of February 19, the U.S. had administered more than 70 million doses of the two authorized vaccines made by Pfizer-BioNTech and Moderna and had distributed more than 94 million doses. 

A CDC report released February 19 revealed that severe reactions to the Pfizer-BioNTech and Moderna COVID-19 vaccines are rare, offering reassurances of safety as efforts for wide-spread vaccination continue to ramp up. The report documented only 4.5 cases of anaphylaxis per million doses of vaccine administered during the reporting period, which the CDC notes is comparable with rates for other types of vaccines. U.K. regulators have also published safety data for the Pfizer-BioNTech and AstraZeneca-Oxford vaccines showing that most side effects are mild and consistent with what is typical of other vaccines. Still, as a precautionary measure, U.K. officials have advised people with a history of serious allergic reactions not to get Pfizer-BioNTech vaccine. 

Vaccine prospects

Here are the vaccines that have made it to phase three and beyond:

Johnson & Johnson

Name: JNJ-78436735

Who: One of the world’s largest multinational corporations, based in New Jersey, specializing in healthcare and pharmaceutical products.

What: A single-dose vector vaccine.

Latest news: On March 2, the U.S. announced that Johnson & Johnson has partnered with its competitor Merck to increase the supply of its COVID-19 vaccine. Merck will dedicate two facilities to producing the vaccine, which could double the amount of available doses. Biden said that the additional doses will allow the U.S. to vaccinate all adults by the end of May rather than the end of July, as previously estimated. The announcement comes days after the FDA authorized Johnson & Johnson’s vaccine for emergency use in the U.S. (Here’s how the Johnson & Johnson vaccine works.)

Approval status: Approved for use in the United States and Bahrain.

Distribution: Johnson & Johnson says that will ship a few million doses immediately, and that it will deliver 100 million doses within the first half of the year, according to the Washington Post

Efficacy and safety: On February 24, an FDA analysis confirmed Johnson & Johnson’s earlier report that its vaccine is safe and effective in preventing COVID-19. The report found the vaccine is 72-percent effective in preventing COVID-19 based on U.S. trials, and 85-percent effective in preventing severe disease across all regions. It also shows that the vaccine was 64-percent effective in preventing disease in the company’s South African trials, which is higher than had previously been reported. 

On October 12, Johnson & Johnson announced that it paused phase three trials for an independent safety review due to an unexplained illness in a participant. The company didn’t provide any details, in part to protect the patient’s privacy, but said that illnesses and accidents are expected in large clinical studies. What’s more, study pauses are routine for clinical trials and aren’t typically reported. On October 23, the company announced it would resume trials.

Clinical trials status: On September 23, Johnson & Johnson announced the launch of its phase three “ENSEMBLE” trial to evaluate the safety of the vaccine—and how well it works—among up to 60,000 adults from a variety of countries. The trial will include “significant representation” from older populations and those with underlying conditions that make them more susceptible to COVID-19. The company announced on December 17 that the trial was fully enrolled with 45,000 participants.

On November 15, Johnson & Johnson launched a second phase three trial to study the safety and efficacy of a two-dose regimen of its vaccine candidate in up to 30,000 volunteers worldwide. The study intends to assess whether a second dose of the vaccine will offer longer-lasting protection.

Moderna Therapeutics

Name: mRNA-1273 

Who: A Massachusetts-based biotech company, in collaboration with the National Institutes of Health.

What: A nucleic-acid vaccine that requires two doses. 

Latest news: On February 24, Moderna announced that it has shipped doses of a booster vaccine to the U.S. National Institutes of Health for clinical study. The phase one trial will determine whether the booster can improve immunity against the South Africa variant. Moderna is also investigating using a third dose of its approved vaccine to protect against variants. 

Approval status: On December 18, the FDA granted emergency approval to Moderna’s COVID-19 vaccine, a day after an advisory panel decided 20-0, with one abstention, that the benefits of the vaccine outweigh the risks, such as the mild side effects reported in their clinical trial. The vaccine has also been approved in the European Union, Canada, the U.K., and Israel.

Distribution: Moderna’s candidate was the second vaccine to receive emergency authorization in the U.S., joining Pfizer’s candidate. On December 11, the Trump administration purchased an additional 100 million doses of Moderna’s vaccine. Two months later, the Biden administration procured an additional 100 million doses, for a total of 300 million by the end of July. On February 12, the New York Times reported that the FDA also told Moderna it can add up to 40 percent more of the vaccine in each vial, increasing the doses inside from 10 to 14. The FDA and Moderna are still in discussions, but the change could help the U.S. more rapidly increase its available supply. 

The company also says it remains on track to deliver at least 500 million doses globally per year beginning in 2021, thanks in part to a deal it has struck with Swiss manufacturer Lonza that will allow it to manufacture up to a billion doses a year. The company said its vaccine can be safely stored on ice or in a normal refrigerator for 30 days.

Efficacy and safety: On February 17, the New England Journal of Medicine published a preliminary report showing that Moderna’s vaccine remains effective in protecting against the virus variant found in the U.K. However, it may be less effective in protecting against the South African variant—although researchers noted that further study is needed. 

In December, an FDA analysis of the phase three study of Moderna’s vaccine confirmed that it is 94.1-percent effective in preventing mild cases of COVID-19 and 100-percent effective at preventing severe cases after taking two doses.

Clinical trials status: Moderna announced on December 17 that it is launching clinical trials to evaluate the vaccine’s safety in children and people with cancer; it will also establish a “pregnancy registry” to track the vaccine’s safety in people who are pregnant. 

The company started the third phase of its clinical trials in July. Preliminary findings from its phase one trials showed that healthy subjects—including elderly patients—produced coronavirus antibodies and a reaction from T cells, another part of the human immune response. Phase three is testing the vaccine in 30,000 U.S. participants. The company also announced plans to test the safety and efficacy of a booster shot that would be delivered a year after the first pair of vaccine doses, according to CNBC. The trial will likely begin in July 2021.


Name: BNT162b2

Who: One of the world’s largest pharmaceutical companies, based in New York, in collaboration with German biotech company BioNTech.

What: A nucleic-acid vaccine that requires two doses taken 21 days apart.

Latest news: On February 25, the journal The Lancet published two studies from Britain that showed the Pfizer-BioNTech vaccine offers strong protection with just one dose. The findings confirm an earlier study of the Israeli vaccination campaign showing that the Pfizer-BioNTech vaccine being used there is 85-percent effective in protecting against COVID-19 within 15 to 28 days after the first dose. The findings could allow governments to expand their vaccination campaigns by delaying the second dose. 

Approval status: On December 2, the U.K. became the first Western country to approve any COVID-19 vaccine when it authorized the Pfizer-BioNTech candidate—making the drug the first mRNA vaccine in history allowed for human use. The FDA granted emergency approval to this vaccine on December 11, a day after an advisory panel decided 17-4 that the benefits of the candidate outweigh the risks for anyone over the age of 16. The vaccine has also been granted emergency approval in Canada, the European Union, and other countries.

Distribution: Pfizer and BioNTech have signed several contracts with the U.S. government to provide 300 million doses by July 31, 2021. On December 17, the FDA said that extra doses found in vials of Pfizer’s COVID-19 vaccine can be used. Vials normally hold enough liquid for five shots, but after the company rolled out 6.4 million doses, pharmacists discovered that some vials contained enough for two extra shots. On January 22, the New York Times reported that Pfizer will ship fewer vials of its vaccine to the U.S. as a result of the discovery.

Globally, Pfizer expects to be able to produce up to 50 million vaccine doses in 2020 and 1.3 billion doses by the end of 2021. Questions have been raised over the vaccine’s storage, which requires ultra-cold freezers set at minus 70 degrees Celsius (-94 degrees F). On February 19, however, Pfizer and BioNTech said that their vaccine can remain stable for two weeks at temperatures between minus 25℃ and minus 15℃ (-13℉ to 5℉), a common range in pharmaceutical freezers and refrigerators. The finding would allow for easier distribution of the vaccine in communities where ultra-cold storage requirements present a challenge. The companies say they have submitted the new data to the FDA for review. 

Efficacy and safety: On December 10, the New England Journal of Medicine published the results of Pfizer’s phase three study, showing the vaccine was safe and 95-percent effective in protecting against COVID-19 in people 16 and older. The FDA has also published an analysis saying that the Pfizer vaccine is safe and offers strong protection against COVID-19 within 10 days of the first dose, regardless of the recipient’s race, weight, or age.

On February 17, the New England Journal of Medicine published a preliminary report showing that the Pfizer-BioNTech vaccine remains effective in protecting against the virus variants found in the U.K. and Brazil. However, it may be less effective against the South African variant—although researchers noted that further study is needed.

Severe allergic reactions following immunization with the Pfizer-BioNTech vaccine have been reported in many countries. White House advisor Anthony Fauci told CNBC in December that some adverse reactions are expected when a vaccine is distributed to a wider population. Regulators in the U.S. and U.K. have also released reports offering reassurances that severe reactions are rare.

Clinical trials status: On November 18, Pfizer and BioNTech announced the conclusion of their phase three trials. The trials launched in July, enrolling a diverse population in areas with significant SARS-CoV-2 transmission. Pfizer has expanded the trial to include 44,000 people across multiple countries. 

On the same day, Pfizer and BioNTech announced the launch of a phase two/three clinical trial to study the vaccine’s safety and efficacy among 4,000 pregnant women over the age of 18.

AstraZeneca-University of Oxford

Name: ChAdOx1 nCoV-19 

Who: The U.K. university, in collaboration with the biopharmaceutical company AstraZeneca.

What: A viral vector vaccine that requires two doses.

Latest news: On February 26, Canada authorized use of the AstraZeneca-Oxford vaccine, making it the third COVID-19 vaccine available for use in the country. The country expects to receive half a million doses within days and more than 20 million additional doses in the months ahead. 

Approval status: Approved for use in the United Kingdom, the European Union, Argentina, India, and other countries.

Efficacy and safety: On February 3, AstraZeneca and Oxford released a preprint study of a phase three trial showing that their vaccine is 76-percent effective at preventing COVID-19 after one dose, with no severe cases or hospitalizations reported. The data also suggest that the vaccine may reduce asymptomatic transmission of the virus. Weekly swabs of participants testing for the presence of the virus found a 67-percent reduction in positive swabs after the first dose. 

The companies also said that the vaccine’s efficacy increased to 82 percent when the second dose was taken after 12 weeks or longer, rather than the originally recommended four-week interval. The British government has recommended the longer gap in its rollout of the vaccine to prioritize getting the first shot to as many at-risk people as possible. 

On December 8, The Lancet published an interim analysis of four of Oxford’s phase three trials. It backed up Oxford’s November 23 claim that the vaccine was 90-percent effective when given as a half dose followed by a full dose one month later. 

On February 7, South Africa halted its use of the AstraZeneca-Oxford vaccine after preliminary laboratory studies showed it offered only minimal protection against the virus variant that is dominant in that country. The WHO has since said it still recommends the vaccine for use. Early data suggested that the vaccine will still effectively protect against the variant that is prevalent throughout the U.K.   

Distribution: Project members say their candidate can be stored at temperatures seen in common refrigeration. Oxford and AstraZeneca expect to produce up to three billion doses of the vaccine in 2021.

On December 30, the U.K. announced changes to its vaccine delivery plan: With COVID-19 infections spreading rapidly, the country said it would prioritize delivering the first dose of either vaccine to as many at-risk people as possible, based on data provided to and released by health regulators.  It will do so by delaying administration of the second dose of the AstraZeneca-Oxford drug. A similar rule was issued for the Pfizer-BioNTech vaccine, but regulators didn’t provide data to back the new regimen. Overall, the U.K. still recommends that recipients receive two doses of either vaccine for maximum benefit. 

On February 15, the WHO listed the AstraZeneca-Oxford vaccine for emergency use, which will allow the agency to begin rolling out the vaccine in low-income countries through the COVAX Facility. Reuters reports that COVAX plans to deliver nearly two billion doses to more than 90 low- and middle-income countries by the end of the year.

Clinical trials status: On December 11, AstraZeneca and Russia’s Gamaleya Institute announced plans to work together to study the possibility of combining Oxford’s vaccine with Gamaleya’s Sputnik V vaccine. Since both use the same adenovirus, researchers will investigate whether a combination of the two will improve efficacy. 

The AstraZeneca-Oxford vaccine’s phase three trial aims to recruit up to 50,000 volunteers in Brazil, the U.K., the United States, and South Africa. On September 8, AstraZeneca paused the trials for a safety review due to an adverse reaction in one participant in the U.K., which the company described as a “routine action.” After an investigation by independent regulators, the trials resumed in the U.K., Brazil, South Africa, and India in September and resumed in the U.S. a month later.

Chumakov Center

Name: CoviVac

Who: A Russian research center.

What: An inactivated vaccine given in two doses, 14 days apart.

Approval status: On February 20, Russia approved the CoviVac vaccine for use even though late-stage clinical trials to test its safety and efficacy have not yet begun. Reuters reports that early-stage trials with 200 participants showed the vaccine has no side effects.

Distribution: The Chumakov Center plans to produce half a million doses per month.

The Gamaleya National Center of Epidemiology and Microbiology

Name: Sputnik V

Who: A Russian research institution, in partnership with the state-run Russian Direct Investment Fund.

What: A viral vector vaccine that uses two strains of adenovirus and requires a second injection after 21 days to boost the immune response.

Latest news: On February 19, the African Union announced that Russia had offered them 300 million doses of the Sputnik V vaccine, which they will make available starting in May. The AU has also secured an additional 270 million doses of the AstraZeneca-Oxford, Pfizer-BioNTech, and Johnson & Johnson vaccines.

Approval status: In August, Russia cleared the Sputnik V vaccine for widespread use and claimed it as the first registered COVID-19 vaccine on the market—before the vaccine’s phase three trials had begun and despite the lack of published evidence at the time. It has since been approved in Belarus, Argentina, Venezuela, and other countries.

Efficacy and safety: On February 2, the medical journal The Lancet published the results of a phase three trial in Moscow that found the Sputnik V vaccine is safe and 91.6-percent effective in preventing COVID-19. The study, which involved more than 22,000 participants, also showed the vaccine is 100-percent effective in preventing moderate or severe cases of the disease, as no such cases were confirmed at least 21 days after receiving the first dose.

Clinical trials status: On December 11, the Gamaleya Institute and biopharmaceutical company AstraZeneca announced they will work together to study the possibility of combining Sputnik V with the candidate that AstraZeneca has developed with the University of Oxford. Since both candidates use the same adenovirus, researchers will investigate whether combining them will improve efficacy of the AstraZeneca vaccine, which is 70.4-percent effective in preventing COVID-19.


Name: NVX-CoV2373

Who: A biotechnology company based in Gaithersburg, Maryland.

What: A protein vaccine that involves a nanoparticle carrier to better aid delivery and uptake by cells.The vaccine is administered in two doses, 21 days apart.

Latest news: On February 4, Novavax said that it has started a rolling review of its vaccine with multiple regulatory authorities—including in the U.S., U.K., European Union, and Canada—to expedite the approval process. The New York Times also reported that the company seems to be making quick progress after a delayed start, and that approval could come as early as April.

Approval status: Not approved for use.

Efficacy and safety: On January 28, Novavax announced preliminary results of its phase three trials in the U.K., which show that its vaccine is 89.3-percent effective in preventing COVID-19. However, preliminary results from the company’s phase 2b trial in South Africa showed a steep drop to 49.4-percent efficacy against the seemingly more contagious variant of the virus first identified in that country. Approximately 90 percent of the COVID-19 infections that occurred during the South Africa trials can be attributed to the variant, according to Novavax. The company said it is working to develop a booster vaccine to better protect against all the emerging virus variants.

On September 2, a study of the company’s phase one trial published in the New England Journal of Medicine found that the vaccine was safe and produced coronavirus antibodies at a higher level than is seen among those who have recovered from COVID-19. It also stimulated T cells, another arm of the human immune response.

Clinical trials status: On September 24, Novavax announced the launch of its phase three trial in the United Kingdom, which will evaluate the vaccine in up to 10,000 people, both with and without underlying conditions. Up to 400 participants will also be vaccinated against the seasonal flu as part of a sub-study that will help determine whether it is safe to give patients both vaccines at the same time. On November 30, Novavax said it had completed enrollment in its phase three trial in the U.K.

On December 28, Novavax announced the launch of a phase three study in the U.S. and Mexico, which will evaluate the safety and efficacy of its vaccine in up to 30,000 adults.

Bharat Biotech


Who: An Indian biotechnology company, in collaboration with the Indian Council of Medical Research and the National Institute of Virology.

What: An inactivated vaccine, which requires two doses that are administered 28 days apart.

Latest news: On January 21, The Lancet published interim findings from COVAXIN’s phase one study that showed the vaccine elicited an immune response in participants. The study identified only one serious adverse event, and it was unrelated to the vaccine. The biotechnology company has not yet published data from its ongoing phase three trials but said in a statement that the vaccine “has generated excellent safety data with robust immune responses.”

Approval status: Authorized for emergency use in India.

Distribution: India has the second-highest caseload in the world—only behind the U.S.—with more than 10 million people infected. As a result, the country is embarking on an ambitious plan to vaccinate 300 million frontline workers and vulnerable people by August 2021.

On January 12, Bharat Biotech announced that it had signed an agreement with Precisa Medicamentos, a Brazilian pharmaceutical company, to sell COVAXIN in Brazil.

Efficacy and safety: Results posted online in September but not yet peer reviewed show that the vaccine produced antibodies in monkeys. Bharat Biotech Executive Director Sai Prasad also told Reuters in October that preliminary results from early vaccine trials found more than 90 percent of human participants developed antibodies.

Clinical trials status: On November 16, Bharat Biotech announced it has begun phase three trials involving 26,000 participants at more than 25 centers across India.


Name: None

Who: China’s state-run pharmaceutical company, in collaboration with the Wuhan Institute of Biological Products.

What: Two inactivated SARS-CoV-2 vaccines.

Latest news: On January 21, Pakistan’s foreign minister announced that China has agreed to provide them half a million doses of the Sinopharm vaccine for free by January 31. Pakistani regulators approved the vaccine for emergency use earlier in the week.

Distribution: Authorities in China have set a goal to vaccinate 50 million people by Lunar New Year in mid-February, despite the lack of evidence that their available vaccines are safe and effective. Chinese officials have said the vaccine will be free for Chinese citizens, and that they will prioritize immunizations for high-risk groups such as the elderly and people with underlying conditions.

On January 13, Hungary’s government announced that it had reached a deal with Sinopharm to buy the company’s vaccine, following Hungary’s criticisms of the pace of the European Commission’s vaccine rollout.

Approval status: China has approved one of the company’s vaccines for general use and another for limited use. One of the Sinopharm vaccines has also been approved in Bahrain, the United Arab Emirates, and other countries.

Sinopharm filed for final regulatory approval from China in late November, two months after the New Yorker reported that hundreds of thousands of Chinese civilians have already been vaccinated under the government’s emergency-use approval. China began to innoculate medical workers and other high-risk groups with the Sinopharm trial vaccines in July, making it the first experimental vaccine available to civilians beyond clinical volunteers.

Efficacy and safety: On December 30, the company announced results of its phase three study showing one of its vaccines to be 79-percent effective in preventing COVID-19. The company did not provide any data backing up its claim. In its earlier approval of a Sinopharm vaccine, the UAE said that an interim analysis of the phase three study showed the candidate is 86-percent effective in preventing COVID-19 with no serious safety concerns. UAE officials also claimed the vaccine is 100-percent effective in preventing moderate and severe cases of the disease.

Preliminary findings from two randomized trials, published in the Journal of the American Medical Association, have shown the vaccine can trigger an antibody response with no serious adverse effects. The study did not measure T cell-mediated immune responses. These results are significant, though, as they are the first published data from human clinical trials for a COVID-19 vaccine that uses a whole, inactivated virus.

Clinical trials status: Sinopharm launched its first phase three trial in July among 15,000 volunteers—aged 18 to 60, with no serious underlying conditions—in the UAE. The company selected the UAE because it has a diverse population made up of approximately 200 nationalities, making it an ideal testing ground. Sinopharm will also undertake phase three trials in locations such as Peru and Bahrain.


Name: CoronaVac

Who: A Chinese biopharmaceutical company, in collaboration with Brazilian research center Butantan.

What: An inactivated vaccine.

Latest news: On January 11, Indonesia’s food and drug agency gave emergency use authorization to Sinovac’s vaccine and began administering it two days later. News of the rollout follows the January 8 move by Indonesia’s highest Islamic body to give religious approval to CoronaVac. The country had already received a total of three million doses of the vaccine.

Approval status: Approved for limited use in China and Indonesia.

Efficacy and safety: Reports released in early January place CoronaVac’s efficacy below that of other authorized vaccines. A late-stage clinical trial in Indonesia found CoronaVac’s efficacy rate to be 65.3 percent. On January 7, Brazilian officials announced that an in-country trial of the vaccine pointed to an efficacy of 78 percent. However, results from the trial released on January 13 found that CoronaVac had an efficacy of 50.4 percent, slightly more than the 50-percent minimum recommended by the World Health Organization. The difference comes down to the earlier estimate’s exclusion of trial participants who got “very mild infections” but did not require clinical assistance.

On November 17, preliminary results from Sinovac’s early trials, published in The Lancet, reported that the vaccine was safe but produced only a moderate immune response, with lower levels of antibodies compared to those in patients who have recovered from COVID-19. Preliminary results in macaque monkeys, published in Science, revealed that the vaccine produced antibodies that neutralized 10 strains of SARS-CoV-2.

Clinical trials status: CoronaVac entered phase three trials in July, with plans to recruit nearly 9,000 healthcare professionals in Brazil, in addition to phase three trials in Indonesia. A planned trial in Bangladesh was delayed, after Bangladesh refused in October to co-finance a late-stage trial.

Murdoch Children’s Research Institute

Name: Bacillus Calmette-Guerin BRACE trial

Who: The largest child health research institute in Australia, in collaboration with the University of Melbourne.

What: For nearly a hundred years, the Bacillus Calmette-Guerin (BCG) vaccine has been used to prevent tuberculosis by exposing patients to a small dose of live bacteria. Evidence has emerged over the years that this vaccine may boost the immune system and help the body fight off other diseases as well.

Latest news: On November 10, a U.S. study published in the Journal of Clinical Investigation found that among 6,201 healthcare workers in Los Angeles, those who had previously received the BCG vaccine reported symptoms of COVID-19 less often than those who hadn’t, a finding that study authors say strengthens the case for further research. In October, the U.K. launched a study of the BCG vaccine that is part of the Australian-led trials. The study is seeking to recruit 1,000 frontline health-care workers to test the vaccine’s effectiveness against COVID-19.

Clinical trials status: In April, researchers from the Murdoch Children’s Research Institute began a series of randomized controlled trials that will test whether BCG might work on the coronavirus as well. They aim to recruit 10,000 healthcare workers in the study. In an April 2020 scientific brief, the World Health Organization found that there is no current evidence that the BCG vaccine protects people against infection with the coronavirus.

Approval status: Not approved for use.

CanSino Biologics

Name: Ad5-nCoV

Who: A Chinese biopharmaceutical company.

What: A viral vector vaccine.

Latest news: A Russian pharmaceutical company Petrovax announced that more than 90 percent of participants in Russian trials of Ad5-nCoV had high levels of antibodies, but few additional details are currently available. Indonesia has ordered 20 million doses of CanSino’s vaccine; Mexico signed an agreement to buy 35 million doses.

Approval status: Though the company was still technically in phase two of its trial, on June 25, CanSino became the first company to receive limited approval to use its vaccine in people. The Chinese government has approved the vaccine for military use only, for a period of one year.

Efficacy and safety: Preliminary results from phase two trials, published in The Lancet, have shown that the vaccine produces “significant immune responses in the majority of recipients after a single immunisation.” There were no serious adverse reactions documented.

Clinical trials status: On December 21, CanSino announced that it has recruited more than 20,000 participants for its phase three trials in Pakistan, Russia, Mexico, and Chile. On August 15, Russian biopharmaceutical company Petrovax announced it had launched the first phase three clinical trial of Ad5-nCoV.

Vector Institute

Name: EpiVacCorona

Who: A Russian biotechnology institute.

What: A protein vaccine, namely it uses small fragments of viral antigens called peptides to produce an immune response.

Latest news: On January 13, Russian state news agency TASS reported that of the more than 2,000 volunteers who had received both doses of EpiVacCorona’s two-dose regimen, none reported adverse reactions from the vaccine. In November, Russia launched mass trials of its EpiVacCorona vaccine; the trials will inoculate 150 people over the age of 60 and 3,000 volunteers over the age of 18.

Approval status: On October 14, Russia granted regulatory approval to EpiVacCorona even though the vaccine candidate has not published any results and has not entered phase three of its clinical trials. It is the second vaccine candidate that Russia has approved for use despite a lack of published evidence about its safety and efficacy.


Name: CVnCoV

Who: A German biopharmaceutical company in partnership with Bayer, a German multinational pharmaceutical company.

What: An mRNA vaccine that’s administered in two doses taken 28 days apart.

Latest news: On January 11, CureVac announced that preliminary results show its vaccine prompted robust antibody and T-cell responses in rhesus macaques. The data have not yet been peer-reviewed.

Approval status: Not approved for use.

Clinical trials status: On December 14, CureVac announced it had begun enrolling participants in a phase 2b/3 study to assess its vaccine’s safety and efficacy in more than 35,000 participants in Europe and Latin America. One week later, the company launched a separate phase three trial in healthcare workers in Mainz, Germany.

Zydus Cadila

Name: ZyCoV-D

Who: An Indian pharmaceutical company.

What: A DNA-based vaccine that is delivered by a skin patch.

Latest news: On January 3, Zydus Cadila announced it had received approval from Indian regulators to launch a phase three trial testing the safety and efficacy of its vaccine in about 30,000 volunteers.

Approval status: Not approved for use.

Safety and efficacy: In December, Zydus Cadila said that a combined phase one/two study of its vaccine showed it was safe and prompted an immunogenic response, but the company did not share any data.

Anhui Zhifei

Name: ZF2001

Who: A Chinese biopharmaceutical company, in partnership with the Institute of Microbiology at the Chinese Academy of Sciences.

What: A subunit vaccine that uses pieces of protein from a pathogen to trigger an immune response.

Latest news: In November, Chinese health officials announced the launch of phase three trials for the Anhui Zhifei vaccine. The trials—which will recruit 29,000 volunteers aged 18 or older—are expected to be conducted in China, Indonesia, Pakistan, and Ecuador.

Approval status: Not approved for use.

Research Institute for Biological Safety Problems

Name: QazCovid-in

Who: A research institute in Kazakhstan.

What: An inactivated vaccine.

Latest news: On January 14, Kazakh health officials granted a nine-month temporary registration to the QazCovid-In vaccine, despite a lack of data from its ongoing phase three trials. Prime Minister Askar Mamin has previously said he expects mass vaccination to begin in March 2021.

Approval status: Granted temporary registration in Kazakhstan.

Clinical trials status: In December, the institute announced that the Kazakh Ministry of Health approved the launch of phase three trials, which will assess the vaccine’s safety and efficacy in 3,000 volunteers.

Institute of Medical Biology at the Chinese Academy of Medical Sciences

Name: Unknown

Who: A Chinese research institute.

What: An inactivated vaccine that requires two doses taken 14 days apart.

Latest news: In December, researchers launched phase three clinical trials to test the efficacy and safety of the vaccine in 34,020 participants in Malaysia and Brazil.

Safety and efficacy: Preliminary results of the vaccine’s phase one trial showed that it prompted an immune response with no serious adverse incidents.

Editor's note: This story was originally published on July 31. It is regularly updated as developments occur.

Read This Next

Rivers and lakes are the most degraded ecosystems in the world. Can we save them?

The world’s oldest known wild bird just turned 70—why she’s so special

Buried for 4,000 years, this ancient culture could expand the 'Cradle of Civilization'

Go Further

Subscriber Exclusive Content

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet