With the LP.8.1.* variant on the way to dominance in most places, it is time to ponder which variant might drive the next wave.
The leading contenders at this point are LF.7.7.2, LF.7.9, NB.1.8.1, XEC.25.1 and XFH.
I show them here using a log scale, so you can compare their growth rates vs the most common LP.8.1.* sub-lineage: LP.8.1.1.
FDA did designate the flu strains for the 2025/2026 season:
egg-based influenza vaccines:
an A/Victoria/4897/2022 (H1N1)pdm09-like virus;
an A/Croatia/10136RV/2023 (H3N2)-like virus; and
a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.
cell- or recombinant-based flu vaccines
an A/Wisconsin/67/2022 (H1N1)pdm09-like virus;
an A/District of Columbia/27/2023 (H3N2)-like virus; and
a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.
Today, the FDA made recommendations to vaccine manufacturers for the virus strains to be used in the trivalent (three strain) flu vaccines for the 2025-2026 U.S. flu season following a thorough and comprehensive review of U.S. and global surveillance data.
Mike Honey
Sam