US FDA advisers recommend flu vaccine strains for 2027 Southern Hemisphere season

By Sneha S K and Siddhi Mahatole

Oct 1 (Reuters) - A panel of advisers to the US FDA on Thursday recommended the virus strains vaccine manufacturers should include for the 2027 southern hemisphere influenza season.

The Vaccines and Related Biological Products Advisory Committee recommended that the egg-based trivalent flu vaccine include H1N1, H3N2 and influenza B strains for the 2027 season. All nine voting members of the committee were in favor.

Trivalent flu vaccines offer protection against three different main groups of influenza Type A and B viruses. All flu vaccines available in the US are trivalent.

"I think our decision this time was very easy, and we just confirmed that not much has changed since the Northern Hemisphere strain selection," Epidemiologist Arnold Monto said.

The advisory committee makes non-binding recommendations to the US Food and Drug Administration, which it generally follows but is not legally bound to do so.

The recommendations followed the FDA's decision to select strains for the 2025-2026 US flu season without an advisory committee vote, after a scheduled meeting was canceled.

Flu season in the US usually occurs in fall and winter. While influenza viruses spread year-round, flu activity peaks mostly between December and February, according to the Centers for Disease Control and Prevention.

Last year's US flu season saw infections rise sharply around the year-end holidays, driven in part by travel and gatherings.

The CDC estimates the 2025-26 season resulted in 32 million to 57 million illnesses, based on preliminary data through May 23.

Seasonal influenza activity, the agency said, is low this year. A total of 31,363 laboratory-confirmed influenza-associated hospitalizations were reported as of September 18.

Vaccine manufacturers project they will produce as many as 135 million doses of flu vaccine for the US market for the 2026-2027 season, according to the CDC.

Sanofi SASY.PA and CSL Seqirus CSL.AX are approved to produce Southern Hemisphere formulations of their influenza vaccines Fluzone and Afluria, respectively, in the US.