The review, although positive, was more nuanced than regulators’ assessments of the first two coronavirus vaccines, reflecting a pandemic that has entered a more complicated phase as variants capable of slipping by some aspects of immunity have emerged. The Johnson & Johnson vaccine was 85 percent effective at preventing severe illness, including in a region dominated by a concerning variant, but only 66 percent protective overall when moderate cases were included.
The FDA scientists found that the “known benefits” of the vaccine included reducing the risk of symptomatic and severe cases of the disease caused by the virus, covid-19, at least two weeks after vaccination. The review found vaccine efficacy against severe covid-19 “was similarly high across the United States, South Africa, and Brazil.”
“We know this vaccine prevents 85 percent of the severe disease … It was 100 percent effective in preventing hospitalization and deaths, and that’s really what’s important,” said Nancy M. Bennett, a professor of medicine and public health sciences at the University of Rochester School of Medicine and Dentistry. “Those facts are the most important thing to recognize.”
The vaccine’s efficacy rate was lower — 42 percent — in preventing moderate to severe illness in a subgroup of adults older than 60 who also had medical risk factors. But regulators noted that the statistical significance was uncertain, and there were no deaths or cases requiring medical intervention a month after those older adults received vaccines. Overall, there were seven deaths in the trial, all in the group that received a placebo.
David Benkeser, a biostatistician at Emory University’s Rollins School of Public Health, said that at this point, the lower efficacy wasn’t a cause of huge concern, but that it warranted more study. He noted that the lower efficacy seemed to be driven by older adults with diabetes, and it would be important to check whether their immune responses to the vaccine were lower.
“There’s a chance that this is a bit of bad luck — if you cut the data up many ways, you are bound to find some puzzling results,” Benkeser said in an email. “For now, the news is overall very positive.”
Still, the lower efficacy among higher-risk older adults could be a topic of discussion when outside experts meet Friday to recommend whether the FDA should authorize the shot. If the regulatory deliberations follow the path of the previous two authorized coronavirus vaccines — a joint vaccine from U.S. pharmaceutical giant Pfizer and German biotech firm BioNTech, and one from U.S. biotech company Moderna — a decision could come this weekend.
Public health officials have eagerly awaited the arrival of the Johnson & Johnson vaccine because it is expected to streamline the logistics of a complicated mass vaccination campaign. The vaccine can be stored in a refrigerator for several months, which should ease the challenges of distributing frozen products, and it doesn’t require a follow-up visit for a booster shot.
The Johnson & Johnson results highlight the challenge variants pose to all of the vaccines: The large, international trial found the vaccine was 72 percent effective at preventing cases of moderate to severe covid-19 in the United States, where variants of concern have only recently begun to be detected. In South Africa, where a variant capable of evading some parts of immunity became dominant late last year, it was 64 percent effective against moderate to severe illness.
That drop-off is smaller than has been seen for some other vaccines. The vaccine developed by Novavax was nearly 90 percent effective in a British trial, but that protection fell to about 50 percent in South Africa. The vaccine developed by AstraZeneca and the University of Oxford, which was estimated to be 76 percent effective in preventing symptomatic infections in trials before variants emerged, was suspended in South Africa after a small d suggested it didn’t appear to protect against the variant there.
Dan H. Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston, whose laboratory helped design the vaccine, said protection against the variant was “quite good,” although he said that all vaccine developers are preparing for the possibility they will need to redesign vaccines for the variants.
Barouch’s work in monkeys provides a clue as to why the vaccine’s protection may have remained robust against the variant. Studies have shown that the antibodies triggered by various vaccines are less effective against the variant first detected in South Africa, leading to fear that vaccines would no longer be protective. But those antibody tests don’t capture the full immune response, and his work showed that the response from another prong of the immune system, T cells, is strongly triggered by the vaccine in animals — and may help explain why the vaccine remains effective.
“The J & J vaccine, if it is approved by the FDA, is going to increase vaccine supply for the country and the world,” Barouch said. “That’s incredibly important, because we need to immunize our country and our world as quickly as possible to end this pandemic and to prevent the emergence of new variants in the future that might be even more concerning than the current ones.”
The results suggest that the immunity from the vaccine will prevent people from the worst outcomes, even if it allows some cases of coughs and fevers to slip by. The vaccine was more than 80 percent effective at preventing severe illness in South Africa.
There was also preliminary evidence that the vaccine may protect against asymptomatic infections, a key question about vaccines throughout the pandemic. Blood tests of 2,650 of the participants found that two months after vaccination, 37 people in the placebo group had markers in their blood that they had been infected despite not having any symptoms, whereas only 10 people in the vaccinated group did — which suggests the vaccine is 74 percent effective at preventing those asymptomatic cases.
The FDA, which on Monday issued new guidance to manufacturers on how to deal with variants, plans to brief the advisory committee Friday on the importance of getting ready for possible updates to vaccines. To streamline the process for getting clearance for modified vaccines, the FDA said, companies will be able to submit smaller studies testing immune responses in people’s bodies rather than lengthy, large trials in which researchers give half the participants a placebo and wait to see if people get sick or not.
Several manufacturers, including Johnson & Johnson, are studying potential modifications to their vaccines to counter variants such as those first detected in the United Kingdom and South Africa.
The vaccine appears to have met the safety and efficacy criteria laid out by the agency — efficacy of at least 50 percent and two months’ worth of follow-up safety data.
The FDA described the vaccine as having a “favorable safety profile,” with the most common side effects including pain at the injection site, headache and fatigue. It said one patient had a “serious event of a hypersensitivity reaction” — an allergic reaction that was not classified as anaphylaxis — two days following vaccination.
If an emergency use authorization is granted, about 2 million doses will be available to ship starting next week to states and other jurisdictions, according to two federal officials familiar with the situation who spoke on the condition of anonymity because they were not authorized to speak publicly. That will make only a small dent in the supply problems afflicting the nation. But supply will ramp up to 20 million doses by the end of March.
But public health experts have also expressed concerns that the public may compare vaccines tested under starkly different circumstances and make judgments about which one they should receive. In Europe, the less-spectacular data supporting the vaccine developed by the University of Oxford and British-Swedish pharmaceutical firm AstraZeneca has led to societal debate over whether people should defer vaccination until they can get one of the other shots, from Pfizer-BioNTech or Moderna.
“We have a really important job to do on how we message this,” said E. John Wherry, an immunologist at the University of Pennsylvania. “The day that an individual has a choice on which vaccine to get — that’s a great day, but probably won’t be until summer.” Until then, he said, people should take the vaccine they can get, because all are robustly effective.
Isaac Stanley-Becker contributed to this report.
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