Flu cases rise on West Coast earlier than usual as US health experts encourage vaccination | US News

Flu cases on the West Coast are rising months earlier than normal, prompting U.S. health experts to stress the importance of the annual vaccine.

Influenza activity generally accelerates in December and reaches its peak in February. But this season started earlier this year, with higher than normal positive cases recorded.

Several experts have attributed the early start to the season to a new mutation in the H1N1 influenza A strain, which caused the 2009 swine flu pandemic.

This strain accounted for 242 of the 300 influenza viruses reported to date by public health laboratories to the Centers for Disease Control and Prevention (CDC).

In California, over the past two flu seasons, the flu test positivity rate was slightly above 1% in early October. As of Oct. 10, that rate was 9.65 percent, according to data from the state Department of Health.

As of Oct. 11, Utah had recorded 242 cases of influenza A, compared to 10 cases at the same time last year, according to Germ Watch, an Intermountain Health database.

Parts of Central Oregon also saw a surge of Influenza A.

Flu vaccines can reduce serious illness and hospitalizations, according to the American Medical Association, which recommends the flu vaccine for everyone 6 months and older.

The 2026-27 flu vaccines, approved by the FDA in August, target H1N1, H3N2 — the dominant strain of last flu season — and an influenza B virus.

Scott Hensley, a microbiologist at the University of Pennsylvania, said two of the three components of this year’s vaccine appear to be very well matched to circulating flu strains.

However, the H1N1 mutation could affect antibodies in younger people, and with flu season accelerating, “it’s probably a good idea to get vaccinated early,” Hensley said by email.

Promotion of flu shots has been scaled back under U.S. Health Secretary Robert F. Kennedy Jr., a longtime anti-vaccine activist who engineered an overhaul of long-standing childhood immunization programs.

Reuters contributed to this report