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FDA advisers recommend updated boosters targeting forms of omicron


A health care worker prepared a Pfizer-BioNTech coronavirus booster shot in Los Angeles earlier this year.

By Sharon LaFraniere and Noah Weiland


An expert committee recommended last week that the Food and Drug Administration plan for updated coronavirus booster shots targeting some form of the omicron variant that has dominated for months.


The panel’s vote paves the way for the FDA to push manufacturers to make reformulated boosters in time for the Biden administration to offer them later this year, before an expected winter surge of the virus.


The decision came after a day of hand-wringing about where the virus is headed next and how best to confront it. A top FDA official called it “science at its hardest.” One committee member described the data as “uncomfortably scant.”


And a top official from one of the vaccine manufacturers, Moderna, told the panel that his company would not be able to make the type of doses that the regulators appear to favor until late October or early November, assuming “no data to assess the vaccine at all.”


“None of us has a crystal ball,” said Dr. Peter Marks, a top FDA regulator who oversees the agency’s vaccines office. “If you do, come over to my house right now. I really would like it.”


Despite all the uncertainties, the panel came down 19-2 in favor of redesigning booster shots to also target omicron or its subvariants, rather than simply the original version of the virus.


“We’re all troubled by the steady erosion of immune protection,” said Dr. Mark Sawyer, an infectious disease specialist with the University of California, San Diego School of Medicine. “We’re going to be behind the eight ball if we wait longer.”


The committee debated but did not specify which formulation might work best. The FDA was clearly leaning toward a combination of the existing vaccine and one tailored to two subvariants of omicron, BA.4 and BA.5. According to new estimates from the Centers for Disease Control and Prevention, those subvariants together now make up more than half of new cases in the country.


That would be a rejection of the booster candidates that Pfizer and Moderna, the two main vaccine developers, have been manufacturing in the expectation that the government would buy doses. The companies had opted for a combination of the existing vaccine and one that targets omicron itself, not its subvariants.


But omicron was squeezed out by its own subvariants almost three months ago, and regulators said in briefing materials that a booster targeting it would be “already somewhat outdated.”


The committee’s recommendation is not binding, but a no vote would have thrown a major wrench in the Biden administration’s efforts to update the existing boosters by the fall. Marks suggested that the agency would follow with its own recommendation “very rapidly.” With booster contracts worth billions hanging in the balance, the manufacturers are expected to follow the regulators’ wishes.


The meeting highlighted the scientific angst over how to combat a virus that is evolving faster than clinical trials involving humans can deliver results. The panel skipped over the divisive question of who should be eligible for a fall booster.


“Right now the critical thing is the manufacturers need to know what to put into their vaccine,” Marks said. “Over the coming months, I think we’ll get a sense and there’ll be plenty of time for debate over who is most appropriate for boosters.”


He predicted that older Americans, at least, might need the next round of protection — a strategy that even some of the more skeptical committee members favor.


Committee members argued for continuing to use the existing vaccines for people who have not yet gotten initial shots. “I don’t think we should lose the prototype,” Dr. Amanda Cohn, a top CDC official, said. “I think it’s a known entity and it’s doing really well in its current job.”


There was little talk about any variant except omicron, which has proved to be a global game-changer.


Dr. Jerry Weir, a senior FDA regulator, said omicron and its offshoots have dominated for about six months, and that whatever incarnation of the virus comes next is more likely to be tied to the omicron family than to earlier versions.


Justin Lessler, a public health researcher with the University of North Carolina at Chapel Hill, presented a series of worrisome projections on the U.S. trajectory of the virus. Under the most optimistic scenario, his team anticipated 95,000 deaths in the 12-month period ending March 2023. Under the most pessimistic scenario, the nation would see over 200,000 deaths.


Although the overall death rate is low compared with earlier in the pandemic, CDC officials said Americans ages 70 and older have driven increases in hospitalizations. Heather Scobie, an agency public health researcher, said that despite “rather poor” uptake, second boosters were reducing the risk of death in older adults and that health officials should “be pushing the second boosters in older ages to protect against serious illness.”


While the committee broadly agreed that a fall booster should be reconfigured to take aim at the omicron family, exactly how was much less clear. Dr. Adam C. Berger, a National Institutes of Health official, voted in favor of an updated booster but said, “I’m not sure that we have evidence to support a change necessarily today.”


Dr. Kanta Subbarao, an adviser to the World Health Organization who presented to the committee, said that she and her colleagues believed a combination of the original vaccine and one targeting omicron alone could provide a broader range of protection and avert the scramble to keep up with the most current variants. The companies presented data showing that such a formulation increased the level of neutralizing antibodies more than the existing booster, but less than twofold and with only a short follow-up period.


Other experts on the panel said they instead favor targeting the BA.4 and BA.5 subvariants that have become the dominant forms of the virus in the United States. Pfizer presented the only data on such a formulation.


Kathrin Jansen, head of vaccine research for Pfizer said that regardless of which formulation the FDA chooses, “We are prepared” to deliver doses by early October, she said. But Dr. Stephen Hoge, president of Moderna, said his company would be able to deliver only by late fall — and only “assuming no clinical data requirements.”


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