Adds details from the meeting throughout

By Puyaan Singh and Christy Santhosh

May 22 (Reuters) - U.S. Food and Drug Administration advisers unanimously recommended on Thursday that COVID-19 vaccines for the 2025-26 period should target newer strains of the JN.1 variant.

COVID vaccine makers are seeing increased regulatory scrutiny under the new FDA leadership, facing tighter requirements for their shots that could increase expenses.

FDA Commissioner Martin Makary and top vaccines regulator Vinay Prasad have both been critical of current U.S. COVID vaccine policies and have indicated that they were under review.

The panel's discussion on Thursday touched upon the prevalence of various strains. Government data indicate that the LP.8.1 strain — a subvariant of the previously recommended JN.1 strain — accounts for about 70% of total cases in the United States.

"We cannot predict the future very far out, but it does seem like (targeting) LP.8.1 is likely to provide us better coverage," said panelist Eric Rubin, adjunct professor at Harvard T.H. Chan School of Public Health.

Shares of vaccine makers Novavax NVAX.O closed 2.5% higher, Moderna MRNA.O 3.6% higher, while those of Pfizer PFE.N closed nearly flat.

The advisory panel also emphasized the need for frequent reviews, given that the dominant strain could change again.

"This virus is still continuing to mutate ... It might be worthwhile to take another look [at vaccine composition] ... particularly for those for whom we are already recommending two doses during the year," said Archana Chatterjee, dean of Chicago Medical School.

However, the committee cautioned that updating vaccines more than once a year would be unfair to manufacturers.

Novavax said on Thursday it was prepared to manufacture an updated vaccine in time for the vaccination season.

Pfizer and its partner BioNTech 22UAy.DE expect to supply the vaccine immediately upon approval, while Moderna hopes to launch it by mid-August.

Based on the panel's discussion, the FDA will soon decide which strain the vaccine makers should target.

(Reporting by Puyaan Singh and Christy Santhosh in Bengaluru; Editing by Mohammed Safi Shamsi)

((Puyaan.Singh@thomsonreuters.com;))