FDA Shifts Gears on Next COVID Boosters, Favoring KP.2 Variant Over JN.1

The U.S. Food and Drug Administration (FDA) has pivoted in its recommendations for the composition of the 2024-25 COVID-19 vaccine boosters. In a surprise move, the health regulator has advised vaccine manufacturers to target the KP.2 variant if feasible, instead of the previously recommended JN.1 lineage.

The FDA's updated guidance, released on Thursday, comes even as Moderna and Novavax – two of the three COVID vaccine makers – had already submitted applications to the agency seeking authorization for updated boosters targeting the JN.1 strain for the fall 2024 season.

Novavax, whose protein-based vaccine manufacturing was already underway for a JN.1 booster, expressed uncertainty about its ability to produce a KP.2-targeting shot for the upcoming fall campaign. The company applied for authorization on Friday, claiming its JN.1 vaccine demonstrated broad cross-neutralizing antibodies against multiple variants, including KP.2 and KP.3. Novavax stated it could have its JN.1 shot ready by mid-July but did not immediately comment on the FDA's preference for a KP.2 booster.

Why It Matters: The FDA's shift in recommendation highlights the ongoing challenge of staying ahead of the rapidly evolving COVID-19 virus. While the agency's advisory panel and global health authorities had recommended targeting the JN.1 strain, the emergence of new variants like KP.2 and KP.3 has prompted a reassessment of the optimal booster composition. The decision underscores the FDA's desire to provide the most up-to-date protection against circulating strains, leveraging the flexibility of mRNA vaccine technology.

The FDA's preference for a KP.2-targeting vaccine deviates from the recommendations of its own advisers, the European regulator, and the World Health Organization, all of which had sought to target the JN.1 strain with updated vaccines. However, Peter Marks, director of the FDA's Center for Biologics Evaluation and Research, had previously expressed interest in offering a KP.2 vaccine option, citing the ability of mRNA shots from Moderna and the Pfizer-BioNTech partnership to be updated quickly.

While JN.1 was the dominant strain in the U.S. earlier this year, accounting for an estimated 3.1% of cases in early June, the KP.2 variant was responsible for about 22.5% of cases, with KP.3 becoming the most prevalent at 25%.

Pfizer stated it is engaging with regulators globally, including the FDA, to assess the composition of future COVID vaccine formulations. Moderna expressed confidence in its ability to deliver the updated shot in time for the fall vaccination campaign, regardless of the final decision on the target strain.

The FDA's evolving guidance underscores the ongoing challenge of staying ahead of the rapidly mutating virus and highlights the potential trade-offs between speed and precision in vaccine development.

Key Takeaways:

• The FDA has recommended targeting the KP.2 variant for 2024-25 COVID boosters, shifting from JN.1.
• Moderna and Novavax had already submitted applications for JN.1-targeting boosters.
• The decision aims to provide protection against the most recently circulating strains.
• Pfizer and Moderna's mRNA technology allows for quicker updates to target new variants.
• The evolving guidance reflects the ongoing race to stay ahead of the mutating virus.