California and Regional Health Surveillance

Wastewater surveillance data from the CDC-affiliated National Wastewater Surveillance System and the WastewaterSCAN project show human metapneumovirus (HMPV), a highly contagious respiratory virus, has been widespread across Northern California this winter, with a sharp peak in January and still-elevated levels in early March. The article reports that HMPV levels are high in communities including San Francisco, Marin, Vallejo, Napa, Novato, Santa Rosa, Sacramento and Davis, and that similar wastewater trends now indicate rapid increases in the Midwest and Northeast as well. HMPV, a single-stranded RNA virus in the same family as RSV, typically causes cough, fever, congestion and shortness of breath but can trigger severe illness such as pneumonia, bronchiolitis and COPD flare-ups in young children, older adults and immunocompromised people, contributing to more than 650,000 hospitalizations worldwide each year. There is currently no vaccine or specific antiviral treatment, so CDC guidance emphasizes testing when appropriate and basic prevention measures such as masking when sick, rigorous handwashing, covering coughs and sneezes, and disinfecting frequently touched surfaces. Public-health experts are watching the wastewater signals as an early-warning system alongside flu and COVID, noting that HMPV’s winter–spring wave appears to be tapering but remains significant in several U.S. regions.