A panel of US medical experts on Tuesday called for Omicron-specific boosters this fall amid growing expectations that Covid vaccines will be needed on an ongoing seasonal basis, as is the case with influenza.
The committee convened by the Food and Drug Administration (FDA) voted 19 in favor and two against the measure after spending a day reviewing available data, including projections of future waves and early results from vaccine makers.
Before the expert meeting, Peter Marks, FDA senior scientist, summarized the complexity of the problem: making predictions about the future course of a virus that has often defied predictions and is mutating even faster than the flu.
“What we’re doing today is working in a very challenging field because none of us have a crystal ball,” he said.
Panelist Michael Nelson, a professor of medicine at the University of Virginia, said he voted “yes” because of concerns that the vaccine’s declining effectiveness would lead to serious consequences for high-risk patients, adding: “We must sooner.” act sooner than later. “
Vaccine makers Pfizer and Moderna previously announced positive data on antibodies elicited by their Omicron-specific vaccines. The two companies made presentations on Tuesday about their mRNA vaccine candidates, as did Novavax on its protein subunit vaccine.
Scientists were not asked to vote on which form of Omicron they would like to see in updated vaccines: BA.1, the original Omicron, or BA.4 and BA.5, which are rapidly gaining ground around the world.
But in their discussion, most experts seemed to favor new vaccines that are “bivalent,” targeting both the original Wuhan strain to generate a broader immune response, and against BA.4 and BA.5, the newest forms of omicron.
Neither Moderna nor Pfizer have mass-produced such vaccines, but officials from the companies said they could start production within three months.
In its presentation, Pfizer said that a prototype booster it developed against BA.4 and BA.5 worked well in mice.
While previous “variants of concern” like Alpha and Delta eventually dried up, Omicron and its sublines have dominated throughout 2022 to the point where it encompasses the vast majority of all Covid in the world, FDA official Jerry Weir said the meeting.
This makes it more likely that future evolution of the virus will occur along the Omicron branch of the Covid family tree. Earlier this month, the World Health Organization also recommended the use of Omicron boosters after a first series against the original strain to elicit a broad immune response.
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