Hidden Virus Hits West Coast, Experts Sound Alarm

A new virus that many people are unaware of is spreading fast along the West Coast. Scientists use wastewater samples to track how common it is in communities, and recent data show that the human metapneumovirus (HMPV) is present in cities such as San Francisco, Sacramento and Davis. The virus reached its highest levels in January but is still high in early March, even as the typical winter surge slows down. HMPV belongs to the same family as RSV and was first identified in 2001. It is a single‑stranded RNA virus, similar to the flu and COVID‑19. While the West Coast sees a sharp rise, other regions like the Midwest and Northeast are also experiencing increases.

People who are most at risk for serious illness include young children, older adults and those with weakened immune systems. The virus can cause cough, fever, nasal congestion and shortness of breath in most healthy individuals. In some cases it may trigger asthma attacks, wheezing, ear infections or even pneumonia. There is no vaccine or specific treatment for HMPV. If someone gets sick, doctors can confirm the infection with a test. Care mainly involves staying hydrated and resting. The Centers for Disease Control and Prevention advises simple steps to reduce spread, such as washing hands frequently, covering coughs and avoiding close contact with sick people. Because the virus is still circulating in many areas, health officials urge everyone to stay alert and follow basic hygiene practices. Monitoring wastewater helps scientists spot outbreaks early, giving communities a chance to respond before the virus spreads further.

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