FDA adcomm votes unanimously in support of a J&J Covid-19 booster two months after one-dose shot
The FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC) on Friday voted 19-0 in favor of authorizing a second shot of J&J’s Covid-19 vaccine to follow at least two months after the initial dose.
Regulators don’t have to follow VRBPAC’s recommendation, but they almost always do. Considering that the CDC’s advisory committee has already been set to review the expanded EUA, VRBPAC’s recommendation is likely to be adopted.
The vote came after Janssen presented data from multiple studies suggesting a second shot provides a significant boost in efficacy compared to the single-dose regimen, including one trial that demonstrated a roughly 94% efficacy rate against moderate and severe Covid-19 in the US. That compares to a 74% US efficacy rate for the single shot, according to Janssen’s final analysis from a separate study.
Today’s meeting could have gone a few different ways, according to the initial voting question, which asked adcomm members to consider data supporting both 2-month and 6-month boosters. While a boost at 2 months increased antibody titers by 3.5- to 6.2-fold, according to Janssen’s global therapeutic head of vaccines Johan Van Hoof, a 6-month boost suggested 9- to 12-fold increases.
However, several VRBPAC members were concerned about the small sample size from the 6-month cohort, which only had data available from 17 patients.
“Although it’s likely to be fine, it’s really hard to make a decision for thousands and tens of thousands and millions of people based on 17 people,” said Paul Offit, a VRBPAC panelist and professor of pediatrics at Children’s Hospital of Philadelphia. “It just seems to me the most logical thing to do at this point would be to say that a second dose is recommended for at least two months later.”
Other adcomm members unanimously agreed, deciding to vote on just the 2-month data for now. Many of them emphasized the urgency of a booster, noting that millions of people who’ve been vaccinated with a single dose are at a higher risk for disease compared to those who’ve received one of the mRNA vaccines.
There are data that suggest the vaccine’s efficacy is even less robust than Janssen suggested in their presentation, the FDA’s top vaccine leader Peter Marks added, due to a lack of available data.
“The idea of the Janssen vaccine as one dose was used as an outreach vaccine. Many of the people who got that may not have been part of a health maintenance organization, or an organized healthcare system, so tracking that may have been challenging,” he said.
Amanda Cohn, executive secretary of the CDC’s Advisory Committee on Immunization Practices, said study results discussed at a Sept. 22 ACIP meeting suggested the Janssen vaccine was only 68% effective against hospitalizations in a group of adults who were not immunocompromised, which is significantly lower than the roughly 80% efficacy rate against hospitalizations than Janssen reported from their real-world study with Aetion.
VRBPAC member Archana Chatterjee, who’s dean of the Chicago Medical School and VP of medical affairs at the Rosalind Franklin University of Medicine and Science, said her initial response to the voting question was no.
“However, having listened to the conversation, and seeing the data in its totality, as well as placing it in the context of these 15 million people who have been vaccinated with a single dose and whose immunity may be waning … This is still a public health imperative,” she said.
Penny Heaton, Janssen’s global therapeutic area head of vaccines, chimed in to specify that the single shot’s response appears to be durable, though less effective than a two-dose regimen.
Some of the VRBPAC members also specified that they would consider another shot the second dose in a two-shot regimen, as opposed to a booster.
“I think this, frankly, was always a two-dose vaccine. I think it’s better as a two-dose vaccine, it’d be hard to recommend this as a single-dose vaccine at this point, given those two month-data,” Offit said.
VRBPAC also voted unanimously yesterday to expand Moderna’s Covid-19 vaccine EUA for booster doses for certain high-risk individuals, just a few weeks after voting to authorize Pfizer’s booster for the same population. Panelist Eric Rubin, editor in chief of the New England Journal of Medicine and an expert on infectious diseases at Harvard’s public health school, noted yesterday that while Moderna’s data “are not perfect,” these are “extraordinary times” — and adcomm members seemed to take the same stance with J&J’s vaccine.
In a mix-and-match study, participants who received J&J’s single shot followed by a Moderna shot saw a geometric mean fold rise (the ratio of post-vaccination titer value to pre-vaccination titer value) of 76-fold, according to Kirsten Lyke of the Center for Vaccine Development and Global Health at the University of Maryland School of Medicine. That compared to a 4.2 GMFR in those who received two doses of J&J’s vaccine, and a 35 GMFR in those who got J&J’s vaccine followed by the Pfizer/BioNTech vaccine.
“What I would note is that the neutralizing antibodies did increase in response to any boost regardless of the primary vaccination series,” she said, also noting that the mRNA vaccines resulted in higher antibody titers in the first 28 days after the boost.
Ofer Levy, a professor of pediatrics at Harvard Medical School and director of Boston Children’s Hospital’s precision vaccines program, expressed concern over recent reports that some Americans are taking matters into their own hands, receiving unauthorized boosters and mixing products.
“In the real world, all these kinds of combinations or extra boosters already happening,” he said. “So I think it’s a matter of some urgency for FDA to help sort out what is admittedly a complicated and challenging scenario. But we can’t hide from it, and I do think we need to give guidance to the public.”