A Food and Drug Administration advisory committee voted Wednesday to update the Covid vaccine formula ahead of a planned fall immunization campaign, now an annual step to try to offer better protection against circulating versions of the virus. .
The unanimous vote of the 16 advisers recommends a formula aimed at combating the JN.1 variant, which dominated infections in the United States in February, or a version of it. In recent weeks, JN.1 has been surpassed by its descendants known as KP.2 and KP.3.
In the coming weeks, the FDA is expected to formally recommend a target variant to vaccine makers for the next round of shots in late summer or early fall. Any decision involves some educated guessing, since any new vaccine formulation won’t be available until months after a variant becomes dominant.
“It is increasingly clear that the ideal time to make a decision on vaccine composition remains elusive,” said Jerry Weir, an official in the FDA’s vaccine division.
Dr. Peter Marks, who oversees that division, urged the committee to consider encouraging mRNA vaccine makers to focus on the latest versions of the virus in wider circulation.
“We always say we shouldn’t be chasing strains, but we’re paying an incredibly high premium for mRNA vaccines so we can have the latest vaccines,” he said, referring to the technology used by Moderna and Pfizer. He compared choosing a vaccine to selecting the freshest milk at the supermarket.
“If this evolves more in the fall, will we regret not having been a little closer?” Dr. Marks asked.
But Dr. Sarah Meyer, a senior vaccine official at the Centers for Disease Control and Prevention, said targeting JN.1 was more appropriate because it was “further up the tree” in the evolution of the coronavirus, which It would possibly allow vaccines to better cover mutations of the virus later this year.
The federal government’s plans for a Covid vaccination campaign, he added, provided for the distribution of a JN.1 option.
“I think it’s really hard to predict what’s going to happen and where things are going to go,” he said.
The advisers’ decision on Wednesday was in line with guidance from the World Health Organization’s expert committee, which recommended in April that Covid vaccines switch to a JN.1 formulation.
FDA advisers reviewed data showing that, as of late May, KP versions of the virus accounted for about half of coronavirus cases nationwide, a sign that they would continue to spread more widely than JN.1.
Representatives from Moderna and Pfizer said the companies would be ready to produce either version of the vaccine.
Novavax, which uses a different vaccine development technology, said it would target JN.1. Dr. Robert Walker, the company’s chief medical officer, said it would be effective in neutralizing strains of KP.
Studies have shown that protection tends to improve as vaccines more precisely target dominant variants, according to the FDA.
On Wednesday, federal officials presented an optimistic portrait of the country’s fight against Covid. Cases were relatively low, said CDC official Natalie J. Thornburg, and data show illnesses from JN.1 were no more severe than from previous variants.
There have recently been fewer than 400 Covid deaths a week, down from a high of about 2,500 a week during the winter, according to initial data collected by the CDC. Older Americans accounted for a significant portion of hospitalized Covid patients.
Last year’s coronavirus vaccination rate was lukewarm. In March, CDC researchers reported that only 18 percent of immunocompromised adults had received the updated vaccine, which provided greater protection against hospitalization. More broadly, just over 20 percent of adults have received the vaccine, CDC data shows.
The lukewarm acceptance of the updated vaccines extended to nursing home residents, who are among the most likely to suffer serious illness, hospitalization or death. CDC data showed that in May, about 30 percent of nursing home residents were up to date on their Covid vaccinations, up from 65 percent two years ago.