An FDA vaccine safety panel had previously recommended the agency authorize the country's third COVID-19 vaccine on Friday following a unanimous vote.
"This is exciting news for all Americans, and an encouraging development in our efforts to bring an end to the crisis," said President Joe Biden in a statement on the authorization. "Though we celebrate today’s news, I urge all Americans — keep washing your hands, stay socially distanced, and keep wearing masks."
Made by Janssen Pharmaceuticals, an arm of Johnson & Johnson, the shot reduced moderate to severe COVID-19 diagnoses by about 66% among vaccinated people a month later, according to clinical trial data reviewed by the panel and FDA scientists. Notably, the shots proved to be 85.4% effective in reducing severe or deadly cases across all coronavirus variants, including the more transmissible ones first identified in Brazil and South Africa.
"It's a relatively easy call — it clearly gets well over the bar," panel member Eric Rubin of Harvard Medical School said after the 22–0 vote. Votes from the panel of outside vaccine safety experts weigh heavily in FDA decision-making, and its positive recommendations shortly preceded the distribution of the two COVID-19 vaccines that have already been authorized.
The unanimous vote reflects the confidence that vaccine experts now have in the safety of such shots overall, after more than 50 million doses have been administered in the US, said panel member Patrick Moore of the University of Pittsburgh Cancer Institute.
"A single dose application offers the opportunity to vaccinate a population faster," said Janssen's Johan Van Hoof, presenting experimental results during the meeting.
The one-dose vaccine offers a more flexible alternative to the two previously authorized mRNA ones, the panelists heard, enabling mass vaccination with its single shot. Jeff Zients, the coordinator for the White House's COVID-19 response team, said on Wednesday that 3 million to 4 million doses of the one-shot vaccine would be distributed next week if the FDA authorizes it. The company says it will deliver 20 million doses to the US by the end of March, and it is obligated to provide 100 million doses by the end of June.
The FDA's analysis of the trial data found a sharp break between vaccinated volunteers and those given the placebo in the incidence of severe or moderate COVID-19 cases starting about two weeks after the shot. "The vaccine appears to offer protection against COVID-19 requiring medical intervention starting at least 14 days post-vaccination," the agency's analysis said. "In the vaccine group, there were no COVID-19 cases requiring medical intervention."
The Janssen vaccine relies on a harmless cold virus, called an adenovirus, that has been given the genes for the spike protein used by the coronavirus to infect people's cells. The vaccine familiarizes the immune system against the spike protein, readying it against the actual coronavirus when it attacks.
Already used for a successful Ebola vaccine, adenovirus vaccines require less care than the Moderna and Pfizer-BioNTech vaccines, easing their administration in pharmacies and smaller clinics. They can be stored in normal refrigerators for up to three months, unlike the existing vaccines. (Late on Thursday, the FDA eased handling for Pfizer's shot, allowing its storage in regular freezers for up to two weeks, instead of ultra-cold specialized freezers.)
As of Friday, around 14% of the US population has received at least one vaccine shot, and more than 80 million doses have been shipped. On Tuesday, vaccine makers Moderna and Pfizer testified to Congress that they expect to have delivered roughly 600 million doses of their already authorized two-shot vaccines by July. That's on top of Janssen's promised one-shot doses, assuring the US will have more than enough doses for its entire population of 330 million people.
"The emergency use authorization of a third vaccine against COVID-19 in the United States today, just over a year since the virus was identified, demonstrates extraordinary scientific commitment and progress," said Infectious Diseases Society of America president Barbara Alexander, in an email sent to BuzzFeed News.
"The availability of another safe and effective vaccine that requires only one dose and that can be stored with only basic refrigeration opens new opportunities for delivery and expanded access for millions of people."
Clinical trial data provided by Janssen support the hope that vaccines may limit transmission of the coronavirus from people who get cases despite the shot, but the findings are too preliminary to be conclusive, FDA scientists said. Last week, Anthony Fauci, chief of the National Institute of Allergy and Infectious Diseases, had pointed to some early results from Israel, where at least 49% of the population has received one shot of the Pfizer vaccine, to suggest that vaccines might help prevent the virus's spread.
Much of the concern about the Janssen vaccine involved findings of lower efficacy of the shot among recipients older than 60 who had other conditions that put them at risk from COVID-19, such as diabetes or obesity. The company responded that this was a concern, but the findings also found that severe cases were limited in this group, similar to all others. "There were no deaths," said Van Hoof.
Janssen is still conducting a large trial, consisting of 30,000 volunteers, for a two-shot protocol of its vaccine. In US testing over fall 2020, the two-dose mRNA shots already authorized by the FDA reduced COVID-19 cases by around 95%. The Janssen vaccine proved to be less effective (around 72%) in US testing over the winter. Janssen officials suggested this partly reflected the spread of coronavirus variants in the last six months that are more resistant to immunization. The B.1.351 variant first identified in South Africa appeared to be somewhat more resistant, with a 64% reduction in cases seen among those vaccinated there a month after the shot. (However, the statistical range of that estimate overlapped with the US result, which means there might be less of a true difference.)
"I have no idea how the two mRNA vaccines would perform in this environment right now with all these different variants running around," Johnson & Johnson's Mathai Mammen told BuzzFeed News in January, when initial results were announced for the one-shot vaccine. "There's no question among thoughtful people out there that the same vaccines run today would have taken a hit in that too."
Vaccine developers were seeing signs that immunity to severe COVID-19 increased after the 28 day cutoff of the clinical trial, said Mammen.
Some epidemiologists have suggested that the similar response seen against severe diseases in all variants in the Janssen clinical trial, with no deaths in the vaccinated group, might point to an interesting driver of SARS-CoV-2 variant mutations. While new variants have perhaps mutated to evade the body's initial antibody response to an infection, that evolution may not apply to the body's subsequent full immune system response — when severe cases turn for the worse. That's because the virus spreads in the early days of infection and not in that dangerous later part. So evolving to evade the immune system later on doesn't provide variants with any advantages in spreading.
Safety data presented to the panel suggest that a little over half of the vaccine recipients reported typical side effects after the shot, such as headaches, fatigue, or soreness. Less than 2% of the people who were vaccinated and reported side effects (against under 1% of the placebo group) said their symptoms were severe ones such as fatigue, fever, or muscle aches.
The FDA did find at least three cases of serious reactions to the shot, including one allergic reaction. But the reactions were not the rare cases of anaphylaxis seen in around five cases per million among mRNA vaccine recipients. Janssen said at the panel meeting that a possible case of anaphylaxis had been recently reported in a separate trial of the vaccine in South Africa, and is under investigation.
On Sunday, a CDC advisory committee panel will take up the question of distribution of the Janssen vaccine, asking whether some groups should be prioritized for the single-shot immunization, which can withstand higher temperatures and rougher handling than the mRNA vaccines. Pharmacies in remote areas might be better suited for single-shot immunization compared to those in urban or suburban regions, for example. That panel will also review federal recommendations on priority groups by age, occupation, and other risk factors in the nationwide vaccine rollout. Pointing to the almost assured FDA authorization of the Janssen vaccine, a vote on the prioritization of the shot was scheduled for Sunday by CDC, ahead of the FDA panel's decision.
"We look forward to our continued efforts around the world as we collectively aim to change the trajectory of this global pandemic," said Johnson & Johnson's Paul Stoffels, in a statement released on Saturday following the approval. The company indicated that it would ask the FDA for full legal licensing of the shot, a measure of approval above and beyond the emergency authorization, later in the year.