This article has been updated.
The Food and Drug Administration gave Covid vaccine manufacturers instructions on what next fall’s Covid vaccines should target on Thursday, signaling it would prefer that they update the strain in their vaccine to a version of the virus that is currently circulating broadly, LP.8.1.
The statement appeared to leave the door open for Novavax, which uses a vaccine production method that requires months of lead time, to stick with an older version of the virus — an option the company indicated it would prefer to do during a meeting earlier in the day of the FDA’s expert vaccines panel.
The instructions were posted to the agency’s website shortly after the end of that meeting of the Vaccines and Related Biological Products Advisory Committee, during which the panel debated the pros and cons of asking manufacturers to update their vaccines for the fall.
VRBPAC members appeared split on whether to advise the FDA to ask manufacturers to update their vaccine target, with a number suggesting manufacturers should be given the option to update or stay with the same target. The committee was not asked to vote on the question, but was asked to express its views.
“FDA has advised the manufacturers of the approved Covid-19 vaccines that to more closely match currently circulating SARS-CoV-2 viruses, the Covid-19 vaccines for use in the United States beginning in fall 2025 should be monovalent JN.1-lineage-based Covid-19 vaccines (2025-2026 Formula), preferentially using the LP.8.1 strain,” the agency said in a press release that was not emailed to reporters and is not featured on the website’s press announcements page.
Earlier this month the World Health Organization’s Covid vaccine advisory committee recommended that manufacturers could either stick with JN.1 or KP.2 strains of the virus, or update to LP.8.1. All these versions of the virus are in the JN.1 family of subvariants, and data presented to Thursday’s VRBPAC meeting suggested that vaccines that target any of these viruses would offer solid protection against related viruses.
Last week the European Medicine’s Agency recommended that manufacturers move to production with the LP.8.1 version of the virus.
During the VRBPAC meeting, some members of the committee appeared concerned that if the FDA recommended a strain change, manufacturers might face new testing requirements that could delay delivery of vaccines for the fall. Some appeared unconvinced that an update would offer markedly more protection.
In the end, the sole vote the committee was asked to take — Should the 2025-2026 vaccine target a JN.1 version of the SARS-CoV-2 virus? — passed unanimously.
The concerns some committee members expressed were triggered by the myriad questions that have been raised by the publication Tuesday of a new Covid vaccine regulatory framework proposed by FDA Commissioner Marty Makary and Vinay Prasad, director of the agency’s Center for Biologics Evaluation and Research. The framework, published in the New England Journal of Medicine, suggests going forward Covid vaccines will only be available to people who are at high risk of severe illness from Covid, because they are 65 or older, or because they have at least one medical condition that elevates their risk.
The pair called on manufacturers to do new randomized controlled trials in younger, healthy adults to see whether Covid vaccination still benefits them, given that most people now have some immunity to the SARS-CoV-2 virus induced by vaccination, infection, or a combination of the two. At a Senate committee hearing on Thursday, Makary estimated conducting those trials would take about a year.
The framework also appears to suggest that manufacturers will be asked to produce human immunogenicity data to support approval of any updated product, a requirement experts say could add weeks or longer to when the products become available. Such data are generated by vaccinating individuals, waiting for an immune response to develop and then studying blood samples to see how much of an antibody increase the vaccine induced. The agency hasn’t indicated how large those studies will need to be.
The press release issued Thursday made no reference to whether immunogenicity studies would be required.
When a member of the committee first asked whether changing the vaccine strain would trigger additional testing requirements, Jerry Weir, director of the FDA’s division of viral products, suggested the question was “a little off topic” and said the agency has only just begun discussions with manufacturers about the new policy. When a second member raised it again later in the discussion, David Kaslow, director of the Office of Vaccines Research and Review, tried to assuage the unease.
“Our goal is not to impact the timely availability of vaccines,” Kaslow. “But we’re really looking to all of you to give us your best judgment in terms of the optimal strain to bring forward.”
Two of the manufacturers, Moderna and the Pfizer-BioNTech partnership, seemed to anticipate a move to LP.8.1. Both make their vaccines using messenger RNA technology, which has a short production time.
But updating vaccine targets without more lead time is more of a struggle for Novavax. In its presentation, the company and its partner, Sanofi, suggested a preference for remaining with the JN.1 virus used for Novavax’s 2024-2025 vaccine.
Robert Walker, senior vice president and chief medical officer, said Novavax could make vaccine doses in time for the fall if it is required to update the virus targeted, but he couldn’t commit to when the vaccine could be delivered. Walker admitted the timeline would be “close.”
The meeting marked the first time since the start of the Trump administration that VRBPAC has been allowed to meet. Though it would normally have been consulted in March on what strains should be included in next winter’s flu shot, the committee was not convened and the FDA issued orders to flu vaccine manufacturers that were based on the suggestions of a WHO-led meeting that occurred in February.
Prasad briefly addressed VRBPAC at the start of the meeting, referring to the framework he and Makary had released, but offering no further clarity on how it will be implemented.
Arnold Monto, a veteran vaccines researcher who chaired the meeting, asked at one point if the framework would be brought to VRBPAC for its input. “For transparency,” said Monto, a professor emeritus in the University of Michigan’s School of Public Health. Prasad had left the meeting at that point and Kaslow was non-committal, saying it might be considered as a “potential topic for a VRBPAC meeting.”
In related Covid vaccine news, the FDA announced Thursday that it is requiring Pfizer and Moderna to put expanded warning labels on their products to warn of the risk of a rare side effect, myocarditis — an inflammation of the heart muscle.
Seen generally in teenage boys — and also seen in this group following Covid infection — the side effect was most commonly reported in the early rollout of Covid vaccines, when people got two doses of vaccine over an interval of three or four weeks. Data presented last month to the expert panel that advises the Centers for Disease Control and Prevention on vaccines showed that reports of myocarditis following Covid vaccination have dropped dramatically since 2021.
Correction: An earlier version of this story incorrectly stated that the European Medicines Agency gave vaccine manufacturers a choice of which version of the Covid virus to target.
