These are the COVID-19 vaccine prospects that have made it to phase three trials and beyond.
BY PUBLISHED
Nurse Kathe Olmstead, right, gives volunteer Melissa Harting, of Harpersville, New York, an injection as part of a study for a possible COVID-19 vaccine developed by Moderna Therapeutics and the National Institutes of Health and Moderna Inc., on July 27, 2020 in Binghamton, New York.Given the urgent need, some vaccine developers are compressing the clinical process for SARS-CoV-2 by running trial phases simultaneously. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, has stated that independent Data and Safety Monitoring Boards can end trials early if their interim results are overwhelmingly positive or negative. Meanwhile, the Trump Administration pressured the U.S. Food and Drug Administration to quickly approve a vaccine by Election Day, which some observers worried was politically motivated. By mid-October, several states—including California, New York, and West Virginia—announced plans to independently review the data for any vaccine the FDA approves. On November 7, the presidential election was called for Democratic challenger Joe Biden.
While the FDA has agreed to expedite the approval process, on October 6 the independent federal agency released more stringent safety standards that had been initially opposed by the White House. In a meeting on October 23, the primary advisory panel for the FDA approval process appeared hesitant to issue an emergency use authorization—which allows the use of an unapproved medical product in a life-threatening situation—to any vaccine candidate. Members said doing so could interfere with ongoing trials; participants may drop out of the trials to ensure they receive the actual vaccine rather than the placebo, which would muddy the data and make it close to impossible to prove the efficacy of a vaccine. CDC director Robert Redfield, vaccine developers, and the FDA have also said it’s unlikely a vaccine will be widely available until the middle of 2021.
Vaccine prospects
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, some 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 coronavirus proteins into a different virus that is unlikely to cause disease or even incapable of it. Finally, some vaccines under development rely on deploying pieces of the coronavirus’s genetic material, so our cells can temporarily make the coronavirus proteins needed to stimulate our immune systems. (Find out more about vaccines and how they work.)
Though it’s too soon to say which candidates will ultimately be successful, here’s a look at the prospects that have reached phase three and beyond—including a quick primer on how they work and where they stand.
Name: BNT162b2
Who: One of the world’s largest pharmaceutical companies, based in New York, in collaboration with German biotech company BioNTech.
What: This vaccine candidate relies on injecting snippets of a virus’s genetic material, in this case messenger RNA (mRNA), into human cells. It spurs the production of viral proteins that mimic the coronavirus, training the immune system to recognize its presence. Any successful vaccine based on this technology would be the first mRNA vaccine approved for human use. This vaccine requires two doses taken 21 days apart.
Status: On November 20, Pfizer and BioNTech said they were filing for emergency authorization from the FDA just two days after announcing the conclusion of their phase three trials. The companies stated that they’ve met their primary goals: The analysis found the candidate to be 95 percent effective in preventing mild and serious cases of COVID-19—and 94 percent effective in adults over 65 years old—with no serious safety concerns. The announcement updates figures from an interim analysis released a little more than a week ago, wherein the companies reported 90 percent efficacy. As yet, they have provided no underlying data to back the claim, and it’s still unclear if the vaccine produces a durable immune response. The companies also haven’t explained if the vaccine works by reducing disease symptoms or blocking the virus entirely. Pfizer has also launched a vaccine delivery pilot program with four U.S. states—Rhode Island, Texas, New Mexico, and Tennessee—to prepare for deployment of the vaccine.
In July, the companies launched a trial that combines phase two and three by enrolling a diverse population in areas with significant SARS-CoV-2 transmission. It has expanded the trial to include 44,000 people across multiple countries. Preliminary results of phase one/two data showed the vaccine produces antibodies and T-cell responses specific to the SARS-CoV-2 protein.
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. It has signed a nearly $2 billion contract with the U.S. government to provide 100 million doses for free, though the New York Times reports that only half its supply will go to the U.S. this year. Questions have also been raised over the vaccine’s storage, which requires ultra-cold freezers set at minus 70 degrees Celsius (minus 94 degrees Fahrenheit).
Name: ChAdOx1 nCoV-19
Who: The U.K. university, in collaboration with the biopharmaceutical company AstraZeneca.
What: Oxford’s candidate is what’s known as a viral vector vaccine, essentially a “Trojan horse” presented to the immune system. Oxford’s research team has transferred the SARS-CoV-2 spike protein—which helps the coronavirus invade cells—into a weakened version of an adenovirus, which typically causes the common cold. When this adenovirus is injected into humans, the hope is that the spike protein will trigger an immune response. AstraZeneca and Oxford plan to produce a billion doses of vaccine that they’ve agreed to sell at cost.
Status: On November 18, preliminary results from Oxford’s phase two trials published in The Lancet, showing that the vaccine produced strong immune responses across all adult age groups, including older adults who are more vulnerable to the disease. Early results also revealed that the vaccine had triggered a strong immune response—including increased antibodies and responses from T cells—with only minor side effects such as fatigue and headache.
The phase three trial now aims to recruit up to 50,000 volunteers in Brazil, the United Kingdom, 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.
Name: CoronaVac
Who: A Chinese biopharmaceutical company, in collaboration with Brazilian research center Butantan.
What: CoronaVac is an inactivated vaccine that uses a non-infectious version of the coronavirus to provoke an immune response.
Status: 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. 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 and Bangladesh. Preliminary results in macaque monkeys, published in Science, revealed that the vaccine produced antibodies that neutralized 10 strains of SARS-CoV-2.
Name: mRNA-1273
Who: A Massachusetts-based biotech company, in collaboration with the National Institutes of Health.
What: This vaccine candidate also relies on injecting snippets of mRNA into human cells to trigger an immune response. This vaccine requires two doses, four weeks apart. (Here’s how mRNA vaccines work.)
Status: On November 16, Moderna announced that an interim analysis of its phase three study shows the vaccine is 94.5 percent effective in preventing COVID-19—including severe cases of the disease—without any significant safety concerns. Like Pfizer, Moderna has not presented underlying data on how the vaccine produced these effects. In a separate announcement, the company also said its vaccine can be safely stored on ice or in a normal refrigerator for 30 days. Moderna intends to apply for an emergency use authorization with the FDA in the coming weeks.
Moderna 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; Moderna expects to have 20 million doses ready to ship in the U.S. by the end of the year and says it remains on track to deliver at least 500 million doses per year beginning in 2021, thanks in part to the deal it has struck with Swiss manufacturer Lonza that will allow it to manufacture up to one billion doses a year. In September, however, Moderna’s chief executive Stéphane Bancel told the New York Times that it was unlikely the vaccine would be widely available in the first half of 2021.
Name: Sputnik V
Who: A Russian research institution, in partnership with the state-run Russian Direct Investment Fund.
What: Gamaleya has developed a viral vector vaccine that also uses a weakened version of the common cold-causing adenovirus to introduce the SARS-CoV-2 spike protein to the body. This vaccine uses two strains of adenovirus, and it requires a second injection after 21 days to boost the immune response. In September, a study of the institute’s phase one/two trials published in the Lancet showed the vaccine produced antibodies and a reaction from T cells.
Status: On November 11—two days after Pfizer’s announcement of its interim results—Gamaleya reported that an interim analysis of its phase three trial found 92 percent efficacy of the Sputnik vaccine. The report was only based on 20 cases, however, which experts say is too few to be convincing. 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.
Name: COVAXIN
Who: An Indian biotechnology company, in collaboration with the Indian Council of Medical Research and the National Institute of Virology.
What: COVAXIN uses an inactivated, or non-infectious, form of the coronavirus that can no longer cause disease but can still provoke an immune response. This vaccine requires two doses that are administered 14 days apart. 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.
Status: On October 23, Bharat Biotech announced it has received approval to start phase three trials in 26,000 participants at more than 25 centers across India.
Name: NVX-CoV2373
Who: A biotechnology company based in Gaithersburg, Maryland.
What: Novavax has bioengineered the coronavirus’s spike proteins, the parts that help the virus invade cells but cannot replicate or cause COVID-19. Its vaccine candidate combines those proteins into a knucklebone-shaped nanoparticle. This can be injected along with its proprietary Matrix-M adjuvant—a compound that stimulates immune cells—to elicit an immune response. The vaccine is administered in two doses, 21 days apart. 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.
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.
Name: JNJ-78436735
Who: One of the world’s largest multinational corporations, based in New Jersey, that specializes in healthcare and pharmaceutical products.
What: Johnson & Johnson is developing an adenovector vaccine, which introduces a piece of DNA from SARS-CoV-2 into the common cold-causing adenovirus that has been genetically changed so that it can’t replicate in the body. This vaccine builds on the technology Johnson & Johnson used to develop an Ebola vaccine as well as vaccine candidates for Zika and HIV. In July, a study published in Nature showed that the vaccine elicited neutralizing antibodies in monkeys and provided “complete or near-complete” protection with just one dose.
Status: On September 23, Johnson & Johnson announced the launch of a 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. On October 12, Johnson & Johnson announced that it has paused these 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 will resume trials.
Name: None
Who: China’s state-run pharmaceutical company, in collaboration with the Wuhan Institute of Biological Products.
What: Sinopharm is also using an inactivated SARS-CoV-2 vaccine that it hopes will reach the public by the end of 2020. Preliminary findings from two randomized trials, published in JAMA, 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.
Status: On September 29, the New Yorker reported that Sinoparm is filing its application to China’s regulatory commission for approval of the vaccine, which could arrive sometime in October. The story also notes that hundreds of thousands of Chinese civilians have already been vaccinated under the government’s emergency-use approval. China began to inoculate 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. Also in July, Sinopharm launched its first phase three trial among 15,000 volunteers—aged 18 to 60, with no serious underlying conditions—in the United Arab Emirates. 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: 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. Researchers are investigating whether these benefits may also extend to SARS-CoV-2, and this trial has reached phase three in Australia. Though as of April 12, the World Health Organization says there is no evidence that the BCG vaccine protects people against infection with the coronavirus.
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.
Name: Ad5-nCoV
Who: A Chinese biopharmaceutical company.
What: CanSino has also developed a viral vector vaccine, using a weakened version of the adenovirus as a vehicle for introducing the SARS-CoV-2 spike protein to the body. 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.
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. On August 15, Russian biopharmaceutical company Petrovax announced it had launched the first phase three clinical trial of Ad5-nCoV.
Name: EpiVacCorona
Who: A Russian biotechnology institute.
What: This candidate is a peptide vaccine, meaning it uses small fragments of viral antigens called peptides to produce an immune response.
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.
Editor's note: This story was originally published on July 31. It is regularly updated as developments occur.
(Sources: National Geographic)
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