A panel of advisors to the Food and Drug Administration voted Wednesday to update the COVID-19 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 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 overtaken by 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 vaccinations in late summer or early fall. Any decision involves some educated guesswork, given that any new vaccine formula won't be available until months after a variant becomes dominant.
“It is becoming clear that the ideal time for 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 to be able to have the freshest vaccines,” he said, referring to the technology used by Moderna and Pfizer. He compared choosing a vaccine to choosing fresh milk at the supermarket.
“If the situation were to evolve further in the fall, will we regret not being a little closer?” asked Dr. Marks.
But Dr. Sarah Meyer, senior vaccines officer 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, possibly allowing vaccines to better cover virus mutations by the end of the year.
The federal government's plans for a Covid vaccination campaign, he added, included the distribution of a JN.1 option.
“I think it's really hard to predict what will happen and where things will go,” he said.
The consultants' decision on Wednesday is in line with the guidelines of the World Health Organization's expert committee, which in April recommended that anti-Covid vaccines switch to the JN.1 formulation.
FDA advisors 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 for Moderna and Pfizer said the companies would be prepared to produce both versions of the vaccine.
Novavax, which uses a different vaccine development technology, said it will target JN.1. Dr. Robert Walker, the company's medical director, said it would be effective in neutralizing KP strains.
According to the FDA, studies have shown that protection tends to improve as vaccines more precisely target dominant variants
On Wednesday, federal officials presented an optimistic portrait of the nation's fight against Covid. Cases were relatively low, said CDC official Natalie J. Thornburg, with data showing that illnesses from JN.1 were no more severe than those from earlier variants.
Fewer than 400 Covid deaths per week have recently been recorded, down from a peak of about 2,500 per week during the winter, according to initial data collected by the CDC. Older Americans made up a significant portion of patients hospitalized with Covid.
Last year's coronavirus vaccination rate was tepid. In March, CDC researchers reported that only 18% of immunocompromised adults had received the updated vaccine, which provided greater protection against hospitalization. More generally, just over 20% of adults have received the shot, CDC data shows.
The lukewarm embrace of updated vaccinations has extended to nursing home residents, who have been among those most likely to suffer serious illness, hospitalization or death. CDC data showed that about 30% of nursing home residents were up to date on Covid vaccines in May, down from 65% two years ago.