The U.S. Food and Drug Administration’s Committee of Independent Vaccine Experts met Thursday to discuss the future of COVID-19 vaccines. The meeting seemed set for an explosive debate. Earlier in the week, the FDA released documents That made it clear that the agency is sticking to its idea that COVID vaccines will fit into the mold of annual flu shots — with reformulations being decided in the first half of each year, followed by fall rollouts in anticipation of winter waves.
But outside experts, including some members of FDA’s Advisory Committee, have questioned nearly every aspect of that plan — from the previously uncertain seasonality of COVID-19 to the futility of chasing down fast-moving variants (or subvariants, as the case may be). Some have even questioned the need to fortify the young and healthy so frequently when current vaccines offer protection against serious disease but only short-lived protection against infection.
One particularly outspoken FDA committee member, Paul Offit, a pediatrician and infectious disease expert at Children’s Hospital of Philadelphia, has publicly attacked the bivalent booster shot, writing an op-ed in the New England Journal of Medicine earlier this month entitled: Bivalent Covid-19 vaccines – a cautionary tale. (The FDA Advisory Committee last year voted 19-2 in support of bivalent boosters, with Offit being one of the two votes against.)
But despite the charged backdrop to yesterday’s meeting, sparks of disagreement flew over a calm discussion. The nine-hour meeting culminated in a unanimous vote by the committee to “harmonize” future formulations of COVID-19 vaccines so that primary series and booster shots are coordinated formulations. For example, the primary series vaccines would match the updated bivalent boosters currently targeting both the original SARS-CoV-2 strain from Wuhan, China and the Omicron subvariants BA.4/5.
rationalization
The FDA seemed to soften the floor with questions and discussion topics focused on “harmonizing” and simplifying COVID vaccines. After the single vote, the agency directed the committee to discuss “simplification of the vaccination schedule” before moving on to the more dangerous but still gentler topic of discussion of considering “regular updates to the COVID-19 vaccine composition.”
Overall, committee members advocated rationalizing vaccines wherever possible, by adjusting initial shots to match booster doses and potentially reducing regimens to one dose for adults and two for high-risk children and adults.
“There is so much confusion about these different phrasings that I think anything we can do to clear up this confusion and simplify things will be a good thing,” said Archana Chatterjee, dean of Chicago Medical School and member of the Voting Committee. said at the end of yesterday’s session. “I agree with my other colleagues that these vaccines are definitely still needed and that we must do our best to get them into arms. Having vaccines is not enough, we need to get them deployed. … This is a step in the right direction to get us there.”
But the bigger steps for future vaccines — deciding what formulation to use next, who should get it and when — remained elephant-sized questions in the briefing room. And even with the relatively quiet comments, it was clear that major arguments were brewing beneath the surface.
Before the committee vote and discussion, the advisors listened to a series of presentations from vaccine manufacturers, the FDA and the Centers for Disease Control and Prevention, all of which provided up-to-date information on the state of COVID-19 and the vaccines’ performance to date.
data dive
Although Offit and others have criticized the bivalent boosters for being no better than the previous boosters, the data presented at the meeting argued otherwise. Real observational data shows an advantage for people boosted with the bivalent booster compared to the original (monovalent) vaccine – even compared to the newer sub-variants. Data presented at the meeting shows that it outperformed the original vaccine in terms of protection against symptomatic infections, emergency room visits or urgent care and hospitalizations.
In a CDC study released WednesdayFor example, the researchers found that the relative vaccine efficacy of the bivalent booster vaccine against symptomatic infections with a BA.5-related omicron subline (comprising BQ.1 and BQ.1.1) was 52 percent in people aged 18 to 49 years . In other words, people in this age group had 52 percent greater protection against infection with BA.5-related strains than people who received the original booster shot. Relative efficacy against BA.5-related infections was 43 percent for those aged 50 to 64 and 37 percent for those aged 65 and over.
Compared to the newer XBB/XBB.1.5-related Omicron subvariants, the relative efficacy against infection was 49 percent in people 18-49 years of age, 40 percent in people 50-64 years of age, and 43 percent in people 65 years and older.
There have also been a number of serological studies examining how the antibody responses of the bivalent booster compare to those of the original booster when compared to the range of omicron subvariants currently circulating. The results are mixed and, in some cases, difficult to compare due to differences in the intervals between vaccinations, the number of people involved, and the types of tests used. But overall, the FDA argued that it suggests the bivalent booster offers better neutralizing antibody responses against currently and recently circulating Omicron subvariants than the original vaccine.
“The important thing is that the results are all going in the same direction,” Jerry Weir, director of FDA’s division of viral products, said at Thursday’s meeting. “In other words, in all of these studies, just like those of the manufacturers, there is improved variant-specific neutralization after administration of the bivalent BA.4/5 vaccine compared to the monovalent… I find it somewhat remarkable to see this level of uniformity.” .”
For example, one of the most recently published studies, published Wednesday in the New England Journal of Medicine, found that a bivalent booster resulted in an approximately three-fold increase in neutralizing antibody levels against XBB.1 compared to subjects boosted with the original booster. This increase was about the same (3.6-fold and 2.7-fold) in people without and with prior SARS-CoV-2 infection, respectively.
Despite criticism from Offit and others before the meeting, committee members seemed pleased with the two-tiered data and accepted the FDA’s rosy review.
“I am absolutely convinced that the bivalent vaccine is beneficial as a primary series and its booster dose,” said committee member David Kim, an infectious disease expert at the Department of Health and Human Services.
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