Human metapneumovirus (HMPV) is spreading rapidly across parts of the United States West Coast, with a notable rise in Northern California. The virus peaked in January and cases were also reported in early March. Public health monitoring through wastewater surveillance has indicated increased activity in cities including San Francisco, Marin, Vallejo, Napa, Novato, Santa Rosa, Sacramento and Davis.
What Is HMPV?
Human metapneumovirus is a respiratory virus first identified in 2001. It belongs to the same viral family as respiratory syncytial virus (RSV). It is a single-stranded RNA virus and can cause illness similar to the common cold. Symptoms include cough, fever, runny or blocked nose, sore throat, wheezing, shortness of breath and, in some cases, rash.
Who Is Most at Risk?
Most HMPV infections are mild. However, severe illness is more likely in:
- Young children
- Older adults
- People with weakened immunity
The virus can lead to hospitalisation worldwide. Its spread has raised concern because respiratory infections often increase during seasonal peaks and can strain healthcare systems.
How It Spreads and Is Managed
HMPV spreads through close contact with infected persons, respiratory droplets from coughs and sneezes, and contaminated surfaces. It is considered highly contagious. There is no specific antiviral treatment for the infection. Medical care focuses on symptom management and support, including oxygen therapy, intravenous fluids and corticosteroids in severe cases.
Prevention and Public Health Response
Preventive measures include frequent handwashing, cleaning surfaces regularly, avoiding close contact with sick individuals and improving ventilation indoors. Wastewater surveillance has become an important tool for tracking respiratory viruses and detecting community spread early. The current rise in HMPV cases marks the need for continued monitoring of seasonal respiratory infections and preparedness in public health systems.
Last Modified: April 28, 2026