MITCHELL, SD (Mitchell Now) — South Dakota is entering the 2025–2026 influenza season following several recent winters with elevated flu activity, according to the South Dakota Department of Health.

State health officials say influenza continues to pose a significant risk for older adults, young children, and people with chronic medical conditions. Those risks can be heightened in rural areas, where longer travel distances and limited access to health care may delay treatment.

Federal health officials are closely monitoring influenza A(H3N2), a subtype historically linked to more severe flu seasons. A newly identified version, known as H3N2 subclade K, emerged in global surveillance after the current vaccine formula was finalized. According to Centers for Disease Control and Prevention surveillance, the subclade now accounts for nearly 90% of H3N2 viruses characterized nationwide.

CDC medical officers say flu seasons dominated by H3N2 strains typically result in higher hospitalization and death rates among adults 65 and older, as well as young children. South Dakota’s aging population and rural geography may increase vulnerability during a severe season.

Health officials continue to recommend annual flu vaccination, even when circulating strains differ from the vaccine. Early national data indicate vaccination reduces the risk of severe illness and emergency care, especially in children. The CDC and the Food and Drug Administration report no evidence that the current H3N2 subclade is resistant to approved antiviral medications.

The South Dakota Department of Health updates flu activity throughout the season via its online dashboard. Officials also encourage residents to stay home when sick, practice good respiratory hygiene, and seek medical care if symptoms worsen.