Idaho Flu Cases Stay 'Very High' as RSV Surges Statewide

Flu activity remains 'very high' across much of Idaho, with federal data showing respiratory syncytial virus, or RSV, on a sharp upward trajectory as of early March.[1] The U.S. Centers for Disease Control and Prevention reported RSV cases 'growing' in the state on March 5, bucking the virus's typical fall-winter peak in December and January.[1] Region 10, encompassing Idaho, Washington and Alaska, saw influenza positivity rates climb in recent CDC surveillance, driven by influenza B alongside dominant A(H3N2) strains.[2] Nationally, the 2025-2026 flu season has logged at least 31 million illnesses, 370,000 hospitalizations and 23,000 deaths, with Idaho mirroring the strain's severity.[2] CDC's Week 13 report pegged weekly hospitalizations at 4.7 per 100,000 residents, while cumulative rates hit 83.7 per 100,000—the third highest since 2010-2011.[2] Pediatric cases are alarming: 139 influenza-associated child deaths reported this season, with children under 18 posting the second-highest hospitalization rates in over a decade.[2] In Idaho, RSV threatens infants under 6 months and older adults most, potentially causing bronchiolitis, pneumonia or breathing support needs.[1] Symptoms overlap confusingly—fever, cough, shortness of breath—for flu, RSV and COVID-19, emerging four to six days post-exposure.[1] The virus spreads days before and up to eight days after symptoms, longer in immunocompromised patients.[1] Idaho's Central District Health and other local agencies echo national calls: Wash hands, mask in crowds, distance, test promptly and hydrate if ill.[1] As April brings variable weather to Boise, Pocatello and rural counties, wastewater surveillance flags moderate national RSV levels, signaling caution.[1] With positivity dipping nationally to 8.2% but rising regionally, Idaho providers like those at St. Luke's and Eastern Idaho Regional Medical Center brace for sustained pressure.[2]