June 14 (Reuters) - The U.S. health regulator has

changed its strain recommendation for the 2024-25 COVID-19

vaccines, as it asked manufacturers to update the new shots to

target the KP.2 variant, if feasible, instead of the JN.1

lineage it sought to target earlier.

The Food and Drug Administration's change in recommendation,

in an update dated Thursday, comes even as Moderna ( MRNA ) and

Novavax ( NVAX ) - makers of two of the three COVID vaccines -

submitted their applications to the agency for updating the fall

2024 season shots with the JN.1 strain.

Novavax ( NVAX ) had said its manufacturing is underway for a JN.1

vaccine and it cannot have a shot this fall for another strain.

The company applied for authorization on Friday and said its

shot showed broad cross-neutralizing antibodies against multiple

variants, including KP.2 and KP.3. It said it can be ready with

its JN.1 shot by mid-July.

Novavax ( NVAX ) was not immediately available for comment on the

FDA's preference for a KP.2 shot.

The FDA's new advisory differs from recommendations of its

own advisers and the European regulator and World Health

Organization, all of which sought targeting the JN.1 strain with

the updated vaccines.

However, FDA's Peter Marks, during the advisory panel's

meeting earlier this month, had said he wanted to give people

the choice of a KP.2-targeting vaccine, counting on the quick

updates possible with messenger RNA shots from Moderna ( MRNA ) and

Pfizer ( PFE ) and its partner BioNTech.

"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," Marks, director of the FDA's

Center for Biologics Evaluation and Research, had then said.

mRNA vaccines can be developed more quickly than Novavax's ( NVAX )

protein-based shot.

JN.1 was the dominant strain in the U.S. earlier this year.

While it is no longer as prevalent, it is estimated to account

for 3.1% of cases over a two-week period ended June 8, the

Centers for Disease Control and Prevention data showed.

The KP.2 variant was estimated to account for about 22.5% of

cases, with KP.3 now becoming dominant at 25%.

Pfizer ( PFE ) said on Friday it was having discussions with

regulators globally, including the FDA, to assess the

composition of future COVID vaccine formulations. Moderna ( MRNA ) said

it would be ready with the updated shot in time for the fall

vaccination campaign, regardless of the final decision on the

strain.

Shares of Novavax ( NVAX ), Moderna ( MRNA ) and BioNTech each closed more

than 3.5% down in the U.S.