The U.S. health regulator on Friday advised COVID-19 vaccine manufacturers that new shots for the fall 2024 campaign should target the JN.1 variant that was dominant earlier this year.

The Food and Drug Administration’s advisory is in line with European and World Health Organization recommendations and comes after the agency’s advisers on Wednesday overwhelmingly backed the targeting of the older JN.1 variant over the newer KP.2 strain.

The advisers recommended the older strain as it is the only strain which Novavax - one of the vaccine makers - said it would be able to target with its shot.

Separately, another vaccine maker Moderna said on Friday it has filed an application with the FDA for its COVID-19 shot targeting the JN.1 strain.

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

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.

Shares of Novavax were down 9% in late morning trade, its second straight session of losses, while Moderna was down 2%. Pfizer was up 0.7%.

Uptake of COVID-19 vaccines, however, has been a concern. Only about 22.5% of adults in the United States received a COVID shot in the 2023-2024 vaccination season, according to data from the U.S. Centers for Disease Control and Prevention that was current through early May.

While JN.1 was the dominant strain in the US earlier this year – it is no longer as prevalent – estimated to account for 3.1% of cases over a two-week period ended June 8, according to CDC data

The KP.2 variant was estimated to account for about 22.5% of cases, with another variant KP.3 now becoming dominant at 25%.

Reporting by Leroy Leo in Bengaluru; Editing by Tasim Zahid and Shailesh Kuber