The seasonal flu in California is surging to levels not seen in several years — though the reasons why aren’t entirely clear.
Test positivity for influenza specimens at state laboratories hit 26% in the week ending Jan. 25 — notably higher than the peaks of the prior four seasons — and is still trending upward, according to the state’s most recent surveillance data on respiratory viruses.
The share of deaths in California related to the flu are also surpassing those of the past four years. As of Jan. 25, 2.4% of deaths in California — 484 people — were attributed to influenza this season, compared to the 1.6% peak of the 2023-24 season and the 1.4% of the 2022-23 season. In 2021-22 and 2020-21, flu deaths were extremely low, likely because COVID-19 isolation dramatically reduced the spread of flu…