“Omicron is clearly in the rearview mirror,” Dr. Peter J. Hotez, a vaccine expert with Baylor College of Medicine, said. A booster that targets Omicron makes no sense, he said, unless it also works against the latest subvariants, adding, “I haven’t seen evidence of that.”
At a meeting on Tuesday, the F.D.A. will ask the advisory panel whether a retooled vaccine should aim at a version of the virus in the Omicron family. That would leave it to federal regulators to decide exactly which formulation to use in the fall.
Scientists initially had high hopes for a so-called bivalent vaccine that would combine the existing formulation with one that targeted Omicron itself. Clinical trial results released this month by Moderna and Pfizer, with its partner BioNTech, found that it triggered higher levels of antibodies against Omicron than existing vaccines do.
But while the companies heralded the findings, outside scientists were not impressed by the less-than-twofold increase.
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