Advisers to the U.S. Food and Drug Administration are scheduled to deliberate this week on whether COVID-19 vaccines should be revised to target the XFG subvariant for the 2026-27 vaccination season, according to documents filed by the agency.
The FDA noted that the ongoing evolution of COVID variants remains rooted in the JN.1 lineage, but that new subvariants such as NB.1.8.1 and XFG have surfaced since May of last year. Earlier this month, the World Health Organization recommended vaccine makers target the monovalent LP.8.1 strain or alternatively focus on currently circulating variants such as XFG or NB.1.8.1.
The advisory committee is due to cast a vote on an updated COVID vaccine formulation on Thursday. The timing of the meeting comes roughly two weeks after commissioner Marty Makary left the agency. Makary's tenure included several contentious decisions, notably stricter requirements for COVID vaccine use, and public disputes with drugmakers over reviews of drugs and vaccines.
Following Makary's departure, Deputy Commissioner for Food Kyle Diamantas has been named acting commissioner. The FDA's vaccine leadership has also seen recent turnover. The agency's vaccine chief Vinay Prasad, who had been critical of current U.S. COVID vaccine policies, stepped down. Earlier in the month, Karim Mikhail was appointed acting director of the FDA's vaccines and biologics unit.
For the 2025-26 season, the FDA had recommended that COVID vaccines target LP.8.1, a subvariant of the JN.1 strain. U.S. Centers for Disease Control and Prevention data showed that, over the four weeks up to April 11, the XFG subvariant was estimated to represent a majority of COVID-19 cases in the United States.
Three COVID vaccines are currently authorized for use in the U.S.: the messenger-RNA-based shots from Moderna and Pfizer-BioNTech, and a protein-based vaccine from Novavax, which has a longer manufacturing timeline. Novavax licensed its vaccine to Sanofi in 2024 under an agreement reported to be worth at least $1.2 billion.
Sanofi, alongside Pfizer and Moderna, is scheduled to present to the advisory committee. The FDA said the manufacturers have indicated they are prepared to manufacture a vaccine formulated against XFG for the 2026-27 season should the advisory panel and regulators move in that direction.
Context and implications
The advisory vote will determine whether regulatory guidance shifts toward an XFG-targeted formulation for next season. The WHO guidance that named LP.8.1 as a recommended target or, alternatively, other circulating subvariants including XFG and NB.1.8.1, sets an international reference point for manufacturers and regulators.
With industry participants slated to present, the committee's decision will inform manufacturers' production plans and regulatory recommendations for public vaccination campaigns.
Presentation participants
Sanofi, Pfizer and Moderna are expected to make presentations to the advisory committee. The FDA noted that those manufacturers have signaled readiness to produce an XFG vaccine for the 2026-27 season if recommended.