Advisers to the U.S. Food and Drug Administration on Wednesday unanimously voted in favor of recommending that COVID-19 vaccines for 2024-25 should target a strain within the lineage of the JN.1 variant that has been dominant this year.

The 16 advisers did not vote on whether to favor the original JN.1 variant or one of its successors like the currently dominant KP.2 strain.

However, during their discussion they overwhelmingly recommended using the older JN.1 variant, particularly as it is the only strain for which Novavax - one of the vaccine makers - said it would be able to target with its shot.

“We wanted to make sure that we gave people the option to potentially make a choice of a KP2 vaccine. We hear loud and clear from all of the members that they don’t feel like that is necessary at this time,” said Peter Marks, director of the FDA’s Center for Biologics Evaluation & Research.

While the agency typically follows its advisers’ recommendation when it makes its final decision, it is not obligated to do.

Shares of Novavax rose 18% on Wednesday, while Moderna closed up 6.5%. Pfizer shares ended marginally higher.

COVID-19 vaccine makers earlier in the day said data from animals studies showed their 2024-25 shots targeting the JN.1 variant that was dominant earlier this year could neutralize newer subvariants such as KP.2 much better than the older shots.

Pfizer and partner BioNTech said they will be ready to supply their updated vaccines immediately upon approval, while Moderna forecasts a timeline for August.

Pfizer and Moderna said they were ready to supply vaccines that target either JN.1 or KP.2 variants.

Vaccines based on messenger RNA (mRNA) from Moderna and Pfizer/BioNTech can be developed more quickly. Pfizer had earlier said it could make the shots in 100 days.

Novavax, which makes a more traditional protein-based shot, said it expects to be ready for commercial delivery of its JN.1 vaccine in the United States in September.

Additional reporting from Richael Erman and Puyaan Singh.