COVID-19 Vaccine Frontrunners
Stay up-to-date on the progress of dozens of vaccine candidates that are currently undergoing clinical testing.
Jef Akst
Apr 7, 2020
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In early March, National Institutes of Allergy and Infectious Diseases Director Anthony Fauci stated that it would take at least a year to a year and a half to get a COVID-19 vaccine approved for use in the US, and that estimate may be optimistic, according to some experts. There are many unknowns this early in the game. How the early candidates will perform, which will be advanced to later stages of clinical development, what safety issues might arise, and how a successful vaccine will be mass produced are among the questions that are now getting attention and funding.
See “Newer Vaccine Technologies Deployed to Develop COVID-19 Shot”
The Coalition for Epidemic Preparedness Innovations (CEPI), a nonprofit dedicated to the development of vaccines against emerging infectious diseases, was one early source of cash for this endeavor, with a total of nearly $30 million invested in several candidates by April. Another bolus of funds came from the Biomedical Advanced Research and Development Authority (BARDA), part of the HHS Office of the Assistant Secretary for Preparedness and Response, which is contributing hundreds of millions of dollars to two top vaccine candidates: one made by Johnson & Johnson’s Janssen division and another developed by Moderna in collaboration with the US government. More recently, the US government’s Operation Warp Speed has invested heavily, giving more than $1 billion each to Novavax and to AstraZeneca, which is collaborating on a vaccine developed by the University of Oxford.
See “US Selects Two COVID-19 Vaccine Candidates for Huge Investments”
Below, The Scientist rounds up those vaccine candidates that appear to be furthest along. But there are many more in preclinical development. “Nobody knows which vaccines are going to work,” Moderna CEO Stéphane Bancel told Science in March.
See “Clinical Trial of COVID-19 Vaccine Begins in Seattle”
Editor’s note: This table was updated on October 16, 2020. New information in bold, red font.
DEVELOPER(S) | VACCINE METHOD | EVIDENCE | STATUS |
Moderna and the US government US | Lipid nanoparticles containing mRNAs for the SARS-CoV-2 spike protein are injected into the arm. | Preliminary results from studies on older adults and those under age 55 suggest that the vaccine is safe and elicits higher levels of SARS-CoV-2 antibodies than does infection with the virus. A third study finds that vaccinated monkeys quickly cleared the virus. Moderna is developing similar vaccines against Zika and other viruses, but to date, no vaccine of this type has been approved for use. | Phase 1, Phase 2, and Phase 3 clinical trials underway across the US |
CanSino Biologics and the Academy of Military Medical Sciences China, Canada, Russia, and Saudi Arabia | Nonreplicating adenovirus 5 (Ad5) vector carrying the gene for the SARS-CoV-2 spike protein is injected into the arm. | Preliminary results from the Phase 2 trial published in The Lancet in July suggest that the vaccine is safe and elicits an immune response, either a T cell response or an antibody response. Adenoviruses are well-established vaccine vectors, and CanSino produced an Ebola vaccine (approved in China in 2017) using the same Ad5 platform. | Phase 1 and Phase 2 clinical trials are underway in Wuhan, China. On June 25, following positive Phase 1 data published in The Lancet on May 22, China’s Central Military Commission approved the vaccine’s use by the country’s military for a year. A Phase 1/2 trial has been approved to begin in Canada. Phase 3 trials have begun in Russia and in Pakistan, and a Phase 3 trial in Saudi Arabia will begin soon, according to Reuters. |
University of Oxford and AstraZeneca UK, US, Brazil, and South Africa | A chimpanzee adenovirus vaccine vector (ChAdOx1) carrying the gene for the SARS-CoV-2 spike protein is injected into the arm. | Preliminary results from the Phase 1/2 trial published in The Lancet in July suggest that the vaccine is safe and elicits strong antibody and T cell immune responses. Six macaques that had received a single dose of the vaccine candidate stayed healthy after being exposed to SARS-CoV-2. A Phase 1 trial using the same adenovirus vector to target MERS is ongoing in Saudi Arabia. | Phase 1/2 and 2/3 clinical trials are underway in the UK, and a Phase 3 trial has begun in the US. Researchers also began testing the vaccine in Brazil and South Africa in June, and additional trials are expected to soon begin in India and Japan. On September 9, all ongoing trials were placed on hold after a serious adverse event arose in a participant enrolled in the Phase 3 study in the UK. Three days later, UK trials resumed. Researchers in the UK will also test an inhaled form in an early-stage trial. |
Inovio Pharmaceuticals US | A special device administers spike protein–encoding DNA molecules through the skin. | Mice and guinea pigs mounted immune responses against the virus, according to a recent preprint, and the company announced interim results from the Phase 1 trial at the end of June that suggested the vaccine was safe and spurred immune responses in 94 percent of the 36 participants analyzed. | Phase 1 clinical trial underway in Pennsylvania, Missouri, and Kentucky with plans to manufacture 1 million doses of its candidate this year |
Sinovac Biotech China, Brazil, Bangladesh, and Indonesia | Inactivated SARS-CoV-2 | In animal studies, the vaccine candidate provides protection against virus strains from different countries. Results from the Phase 2 trial announced in August suggest that the vaccine is safe and elicits an antibody-based immune response. Sinovac had used a similar platform to develop a vaccine against SARS in 2004 that showed promising results in early-stage human trials. | A Phase 1/2 clinical trial is underway in China, and Phase 3 trials are underway in Brazil, Bangladesh, Indonesia, and Turkey. |
Wuhan Institute of Biological Products and China National Pharmaceutical Group (Sinopharm) China and United Arab Emirates (UAE) | Inactivated SARS-CoV-2 | In mid-June, Sinopharm announced that nearly all of the more than 1,000 participants who had received two injections of the mid-dose vaccine tested positive for antibodies against SARS-CoV-2. In August, Phase 1/2 trial results published in JAMA indicated that the vaccine is safe and elicited neutralizing antibodies. | A Phase 1/2 clinical trial is underway in China. A Phase 3 trial is underway in UAE, and another has been approved to begin in Peru. |
Beijing Institute of Biological Products and China National Pharmaceutical Group (Sinopharm) China | Inactivated SARS-CoV-2 | The two-dose vaccine protects rhesus macaques against SARS-CoV-2, according to a paper published in Cell in early June. In mid-October, Sinopharm published results from the early trials in The Lancet showing that the vaccine was safe and that participants receiving the vaccine had high titers of antibodies. | Phase 1/2 clinical trial underway in China |
Symvivo Canada | Orally administered Bifidobacterium probiotic engineered to carry DNA encoding the SARS-CoV-2 spike protein | In addition to this vaccine currently in human testing, two other candidates for COVID-19 are being developed by Symvivo. | Phase 1 clinical trial underway in British Columbia and Nova Scotia |
BioNTech and Pfizer International | Four RNA vaccine candidates are being tested in parallel. | Preliminary results from the early stage trials suggest that the vaccine is safe and elicits higher levels of SARS-CoV-2 antibodies than infection with the virus, according to two preprints posted by the companies in July, one of which was later published in Nature. A second study published in Nature at the end of September reported that the vaccine generated T cell responses in addition to antibody responses. | Phase 1/2 clinical trial underway in Germany, China, and in Ohio, New York, and Maryland in the US. In July, the companies announced that they had picked their lead candidate and had begun a Phase 2/3 trial in the US, Germany, Brazil, and other countries, including a Phase 3 trial that has commenced in South Africa. The companies announced in early October that the vaccine was starting the process of rolling submission with the European Medicines Agency. |
Shenzhen Geno-Immune Medical Institute China | Immune cells (human dendritic cells and T cells, or artificial antigen presenting cells) are engineered to express a synthetic minigene based on SARS-CoV-2 proteins and injected or infused into the patient. | The research institute modifies cells using lentivirus vectors that it has used to develop CAR T cell therapies as well as gene therapies. | A Phase 1/2 clinical trial is underway in China for the dendritic cell and T cell–based vaccines, and a Phase 1 trial is underway for a vaccine using artificial antigen presenting cells. |
Clover Biopharmaceuticals Australia | The vaccine delivers pieces of the SARS-CoV-2 spike protein. | The Trimer-Tag platform used is the basis for other viral vaccines in development. | Phase 1 clinical trial underway clinical in Australia |
Novavax Australia and South Africa | Nanoparticles carrying antigens derived from the SARS-CoV-2 spike protein (with Matrix-M adjuvant) | In 2012, the company started development on a SARS vaccine that served as the basis for its new SARS-CoV-2 vaccine candidate. Data from the Phase 1/2 trial published in The New England Journal of Medicine in early September shows the vaccine candidate to be safe and elicit immune responses greater than those caused by treatment with COVID-19 convalescent serum. | A Phase 1 clinical trial is underway in Australia, and a Phase 2 trial is underway in South Africa. A Phase 1 clinical trial is underway in Australia, and a Phase 2 trial is underway in South Africa. A Phase 3 trial has begun in the UK, The New York Times reports, and late-stage trials are also planned to begin in the US and in India in October. |
Gamaleya Research Institute of Epidemiology and Microbiology, Health Ministry of the Russian Federation, Acellena Contract Drug Research and Development Russia | Adenovirus vector displaying the SARS-CoV-2 spike protein on its surface | Preliminary results from the early stage trial published in September in The Lancet point to the vaccine candidate’s safety and ability to elicit an antibody response. Gamaleya Research Institute Director Alexander Gintsburg announced in May that he and other staff researchers had gotten the vaccine themselves, the AP reports. | Phase 1/2 clinical trials are underway in Russia to test liquid and powder forms of the vaccine. In August, Russian President Vladimir Putin said that the country approved the vaccine ahead of a Phase 3 trial. |
Immunitor Canada and Mongolia | Heat-inactivated plasma from donors with COVID-19 taken as a pill daily for a month | The initial safety test will give volunteers the pill for 15 days. | Phase 1/2 clinical trial underway in British Columbia and Mongolia |
Institute of Medical Biology at Chinese Academy of Medical Sciences, West China Second University Hospital, Yunnan Center for Disease Control and Prevention China | Inactivated SARS-CoV-2 | Data from the Phase 1 trial, posted as a preprint on October 6, suggests that the vaccine is safe and elicits an immune response, although levels of neutralizing antibody started to drop after just two weeks. | Phase 1/2 clinical trial underway in China |
Imperial College London | Self-amplifying RNA molecules are injected into the muscle. | The vaccine platform, which is designed to allow researchers to respond quickly to emerging pathogens, received $8.4 million from CEPI last December. “We cannot predict where or when Disease X will strike, but by developing these kinds of innovative vaccine technologies we can be ready for it,” CEPI CEO Richard Hatchett said at the time. | A Phase 1 trial is underway in the UK. Researchers in the UK will also test an inhaled form in an early-stage trial. |
CureVac Belgium and Germany | RNA vaccine; details not disclosed | CureVac reported in January that a Phase 1 trial of a comparable vaccine for rabies induced immune responses with just 1 microgram of mRNA, meaning it could be easy to scale up to produce mass quantities. | Phase 1 trial underway in Belgium and Germany; company says it could manufacture 10 million doses by that time. |
Medicago | Virus-like particles that resemble SARS-CoV-2 are produced in a close relative of tobacco. | The company has a rotavirus vaccine in clinical trials that is based on virus-like particles, and another for norovirus in preclinical studies. | A Phase 1 trial has been approved |
Altimmune | Undisclosed vaccination delivered intranasally | The company is using the same technology to develop a flu vaccine that is in clinical trials. | A Phase 2 trial has been approved |
AnGes, Japan Agency for Medical Research and Development Japan | Engineered circular DNA encoding the SARS-CoV-2 spike protein | The vaccine consists of two intramuscular injections. | Phase 1/2 trial underway in Japan |
Aivita Biomedical US | A patient’s own dendritic cells are modified to carry SARS-CoV-2 antigens and then reinfused. | Antigen-carrying dendritic cells triggered a response in the same patient’s lymphocytes in vitro. | A Phase 1/2 trial has been approved to begin in California. |
Genexine South Korea | DNA encoding the SARS-CoV-2 spike protein | The vaccine was shown to produce neutralizing antibodies in nonhuman primates. | Phase 1/2 trial underway in South Korea |
Vaxine, Medytox Australia | Recombinant SARS-CoV-2 spike protein plus a polysaccharide adjuvant | Vaxine developed an experimental swine flu vaccine during the 2009 pandemic. | Phase 1 trial approved to begin in Australia |
Zydus Cadila India | Engineered DNA plasmid encoding a SARS-CoV-2 antigen | In a preclinical study, the vaccine neutralized SARS-CoV-2 in a virus neutralization assay. | Phase 1/2 trial underway in India |
Bharat Biotech India | Inactivated SARS-CoV-2 | In guinea pigs and mice, the vaccine was safe and elicited an immune response. | Phase 1/2 trial underway in India |
Janssen International | Nonreplicating adenovirus 26 (Ad26) vector carrying undisclosed genetic material of SARS-CoV-2 is delivered via intramuscular injection. | Janssen published preclinical data in Nature in July demonstrating that the vaccine protected monkeys against SARS-CoV-2 infection. In late September, the company posted a preprint with preliminary results from an early-stage trial that showed a single dose of the vaccine to be safe and to elicit neutralizing antibodies in nearly all study participants. The company is also developing other Ad26-based vaccine candidates, including its Ebola vaccine that was deployed in Democratic Republic of Congo in November 2019. | Early stage clinical trials are underway in the US, Belgium, and Japan. Meanwhile, a Phase 2 trial is scheduled to begin in early September in Spain, Germany, and the Netherlands, and an international Phase 3 trial is being launched in the US, Mexico, several South American countries, the Philippines, South Africa, and Ukraine. On October 12, however, the company announced that it had temporarily paused further dosing in all of these trials after a participant developed an unexplained illness. |
Arcturus Therapeutics Singapore | Self-replicating mRNA encoding coronavirus proteins | The self-replicating mRNA platform is not the basis of any approved medicines, but preclinical results announced in April suggest the vaccine candidate triggers an immune response. | Phase 1/2 trial underway in Singapore |
University of Queensland Australia | Molecular clamp technology presents viral proteins to the immune system. | Preclinical work in cell culture showed that the vaccine candidate elicited an immune response that was capable of neutralizing SARS-CoV-2 infection. | Phase 1 clinical trial underway in Australia |
ReiThera Italy | Proprietary replication-defective gorilla adenoviral (GRAd) vector encodes the SARS-CoV-2 spike protein. | The vaccine candidate was safe and induced an immune response in animal models, according to the company. | Phase 1 trial underway in Italy |
Sanofi and GlaxoSmithKline (GSK) US | Antigen based on SARS-CoV-2 spike protein (with adjuvant) | Sanofi uses the same recombinant DNA technology in a flu vaccine and in a SARS vaccine candidate that never entered clinical trials. Meanwhile, GSK’s adjuvant, AS03, was used in vaccines the company made against the H1N1 and H5N1 pandemic flu viruses. | A Phase 1/2 trial underway in the US |
State Research Center of Virology and Biotechnology “Vector” Russia | Peptide-based vaccine based on a platform developed for an Ebola vaccine candidate | Volunteers in the Phase 2 trial are “feeling good,” the Russian consumer safety watchdog Rospotrebnadzor said in a statement, according to Reuters. | Clinical testing was completed by the end of September, according to Reuters. In October, Russian President Vladimir Putin announced its approval ahead of a Phase 3 trial, NPR reports. |
Vaxart US | A pill containing different SARS-CoV-2 antigens | After testing five different vaccine candidates in animals, the company chose its lead candidate, which generated immune responses after a single dose, for clinical testing. The company has other oral recombinant vaccine candidates that have shown success in clinical trials. | Phase 1 trial underway in California |
ImmunityBio US | A human adenovirus (hAd5) vector delivers SARS-CoV-2 antigens, both the spike protein and the nucleocapsid protein found inside the virus. | The company says it is developing forms of the vaccine for oral, inhalational, and intranasal administration; the oral version will be tested in the initial Phase 1 trial. | Phase 1 trial approved to begin in the US |
| NOT YET IN CLINICAL TRIALS | |||
University of Pittsburgh School of Medicine | Microneedle patch delivers pieces of the spike protein through the skin. | Vaccinated mice produced antibodies specific to SARS-CoV-2 at levels that would likely neutralize the virus, according to a study published in EBioMedicine on April 2. | Expected to start clinical testing within a few months of that publication, according to the university |
Generex Biotechnology | Undisclosed synthetic viral peptides are combined with proprietary Ii-Key immune system activation | The company has had success with the Ii-Key technology for other infectious diseases and for cancer in clinical trials. | Expected to start clinical testing “within 90 days,” the company announced on February 27 |
Takis Biotech and Applied DNA Sciences | The company is exploring five DNA-based candidates based on the SARS-CoV-2 spike protein. | The vaccine candidates contain PCR-produced pieces of linear DNA, as opposed to the more traditional circular plasmids, which could have several advantages including quick production. No vaccines using this approach have yet been tested in humans. | Expected to start clinical testing in the fall |
Merck | A vesicular stomatitis virus (VSV) carries undisclosed viral components | The VSV vector is used for Merck’s existing Ebola vaccine. | Expected to start clinical testing later this year |
Merck | A weakened measles virus vector carries undisclosed viral components | Merck is purchasing Vienna-based Themis, which has an existing measles vaccine, to develop the COVID-19 vaccine. | Expected to start clinical testing later this year |
In addition to vaccine candidates specific to SARS-CoV-2, several trials are underway testing vaccines against different pathogens as well as nonspecific formulations designed to stimulate an innate immune response.
DEVELOPER(S) | VACCINE METHOD | EVIDENCE | STATUS |
Multiple organizations International | The Bacille Calmette-Guerin (BCG) vaccine for tuberculosis consists of live attenuated Mycobacterium bovis. | Lower rates of COVID-19–related deaths in countries with mandatory BCG vaccination prompted the launch of several clinical trials to test whether the immune response triggered by the vaccine may protect against SARS-CoV-2. | Several Phase 3 and 4 trials are underway. |
Multiple organizations International | The measles-mumps-rubella (MMR) vaccine consists of live-attenuated strains of the three viruses. | Epidemiological data have revealed that places where the MMR vaccine is given as standard medical care have lower COVID-19 death rates than areas where MMR vaccination is not standard. Additionally, sailors aboard the U | A Phase 3 trial is underway in Egypt, led by researchers at Kasr El Aini Hospital. Separately, researchers at the Washington University School of Medicine are running an international Phase 3 trial of healthcare workers in the US, Canada, Europe, and Africa. |
Immunovative Therapies, Mirror Biologics US | An off-the-shelf living immune cell | The affiliated companies are currently testing the formulation as a therapeutic vaccine for chemotherapy-refractory metastatic cancers. | A Phase 1/2 trial for healthy older adults has been approved to begin in New York. |
Canadian Cancer Trials Group, others Canada | Heat-killed Mycobacterium obuense | The vaccine is intended to stimulate nonspecific innate immunity. The company is also testing the vaccine in clinical trials for cancer. | |
Bandim Health Project Guinea-Bissau | Oral polio vaccine, an attenuated strain of the poliovirus | Researchers argue that the vaccine is safer and available in greater quantities than the BCG vaccine against tuberculosis, which is also being tested as a possible COVID-19 preventive. | A Phase 4 trial has been approved to begin in Guinea-Bissau in West Africa. |
Inmunotek, BioClever Mexico | A mixture of inactivated bacteria | The vaccine is intended to stimulate nonspecific innate immunity. | A Phase 3 trial for healthcare workers has been approved to begin in Mexico. |
Pulmotect US | An inhaled combination of two synthetic Toll-like receptor agonists | The vaccine was originally developed as a potential therapeutic for cancer and has undergone early stage clinical testing. In mice, it provided protection against a range of respiratory pathogens, including MERS and SARS. | A Phase 2 trial for people with known SARS-CoV-2 exposure is underway in several US states. |
Correction (June 11, 2020): An earlier version of this table stated that Janssen’s adenovirus-based COVID-19 vaccine candidate is administered intranasally. In fact, the vaccine is administered via intramuscular injection.
Correction (July 27, 2020): An earlier version of this table stated that the Phase 1 and Phase 2 Moderna trials were taking place in Seattle. In fact, there have been multiple locations since the Phase 1.
Correction (September 9, 2020): A previous update to this table implied that the adverse event that caused the Phase 3 AstraZeneca trial to be put on hold occurred in the Phase 1/2 trial in the UK. In fact, the event occurred in a participant enrolled in the Phase 3 UK study.
The Scientist regrets the errors.
