Human Metapneumovirus Cases Surge in Northern California

The virus is causing respiratory infections, especially in young children and high-risk individuals.

Published on Mar. 10, 2026

Got story updates? Submit your updates here. ›

Human metapneumovirus (HMPV), a respiratory virus first discovered in 2001, is currently spiking in the U.S., including high levels detected in Northern California wastewater. HMPV causes symptoms similar to the flu and RSV, and can lead to severe illness, especially in infants, young children, and those with weakened immune systems or other underlying health conditions.

Why it matters

HMPV is a lesser-known but potentially serious respiratory virus that is now circulating widely in Northern California. As the region continues to grapple with the ongoing impacts of COVID-19, the surge in HMPV cases adds another respiratory illness that public health officials and the medical community must monitor and respond to.

The details

HMPV spreads through direct or close contact with infected individuals, including exposure to respiratory droplets, aerosols, or contaminated surfaces. Symptoms can range from mild upper respiratory issues to more severe pneumonia or bronchiolitis, especially in high-risk groups like young children, the elderly, and those with weakened immune systems or chronic health conditions.

  • HMPV is a seasonal virus, typically spiking in the U.S. during the spring.
  • Wastewater surveillance data has detected high levels of HMPV in Northern California, including in Sacramento, Davis, Vallejo, and San Francisco.

The players

Dean Blumberg

Chief of pediatric infectious diseases.

National Respiratory and Enteric Virus Surveillance System (NREVSS)

A system that monitors viral activity in the U.S.

WastewaterSCAN

A program that tracks pathogens in wastewater.

Got photos? Submit your photos here. ›

What they’re saying

“HMPV causes symptoms very similar to RSV. This includes upper respiratory symptoms that sometimes progress to pneumonia or bronchiolitis and wheezing.”

— Dean Blumberg, Chief of pediatric infectious diseases (Mirage News)

“Children born prematurely, with heart or lung disease, or weakened immune systems are at higher risk for severe disease.”

— Dean Blumberg, Chief of pediatric infectious diseases (Mirage News)

What’s next

Public health officials and medical providers in Northern California will continue to monitor HMPV cases and provide guidance to the public on prevention and treatment.

The takeaway

As the region navigates the ongoing COVID-19 pandemic, the surge in HMPV cases underscores the need for vigilance against respiratory illnesses, especially for vulnerable populations. Practicing good hygiene and seeking medical care when necessary can help mitigate the spread and impact of HMPV.