Flu cases rise early on US west coast amid strain mutation

Flu cases on the US west coast are rising months earlier than normal, according to the Guardian. US health officials are emphasizing the importance of receiving the annual vaccine as positive tests increase ahead of the usual schedule. [1]

The Guardian reported that California has recorded a flu test positivity rate of 9.65 percent. That figure is significantly higher than the standard 1 percent rate usually observed in early October. [1]

Flu activity typically increases in December and peaks in February, but experts quoted by the Guardian credited the early start to a new mutation of the H1N1 influenza A strain. The H1N1 strain previously caused the swine flu pandemic in 2009. [1]

As FTMQ News reported earlier, respiratory viruses have also been increasing elsewhere, with British flu cases tripling in early October 2026 compared to the previous year. [2]