The number of people sick with flu is starting to increase across the United States, with health authorities warning that in some western regions of the country, the 2026-27 flu season may be off to an early start.

Health authorities often advise people to get their flu vaccine by the end of October – but as an epidemiologist focusing on vaccines and infectious diseases, I see the uptick in activity as a sign that there’s no time like the present.

Several vaccine options are available, including the new mRNA influenza vaccine, approved by the Food and Drug Administration in August 2026.

It’s too early to say for sure that this year’s flu season will be an early one across the entire U.S. or to predict if it will be particularly severe.

As of Sept. 26, the latest date for which data is available, seasonal influenza activity remains low nationally, and wastewater surveillance still shows very low to low activity in most states.

However, the number of patients with respiratory infections who were testing positive began increasing near the end of September, suggesting that influenza viruses are beginning to circulate more widely.

In the U.S., influenza typically starts to........

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