Influenza A cases on the rise

Editor's Note

Seasonal influenza activity remains low nationally but is increasing, primarily among children, according to the CDC weekly influenza report published November 14.

The CDC reported the percent positivity for influenza and the percentage of emergency department visits for influenza among pediatric age groups increased for the week ending November 8, 2025. No influenza-associated pediatric deaths during the 2025-2026 flu season have been reported to CDC.

Specific to influenza subtype, 72 influenza viruses were reported by public health laboratories, with 67 being influenza A and 5 being influenza B. Of the 53 influenza A viruses subtyped for this week, 28.3% were influenza A(H1N1) and 71.7% were A(H3N2). The timing of this influenza uptick is similar to past seasons in the US, including for last year.

In related news coverage, a mutated subtype of influenza A (H3N2) is circulating overseas. For example, in England flu rates have started climbing much sooner than usual, primarily in young adults and schoolchildren. Experts warned in a November 12 news report in thebmj that the H3N2 strain currently dominant in cases in England, mutated seven times over the summer, making it more severe than normal.