Human Metapneumovirus Cases Rise in California

Respiratory virus without vaccine or treatment spreads in parts of state, but officials say no need to panic

Published on Mar. 4, 2026

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Cases of human metapneumovirus (HMPV), a respiratory virus without a vaccine or specific treatment, are on the rise in parts of California, according to data from the WastewaterScan Dashboard. While HMPV typically causes mild, cold-like symptoms, it can lead to more severe disease in vulnerable individuals. Public health officials say there's no need to sound the alarm, but they advise taking precautions to prevent the spread of the virus.

Why it matters

HMPV is not a new virus, but its seasonal spread pattern was disrupted by the COVID-19 pandemic. Its resurgence could signal a return to a more typical pre-coronavirus respiratory disease landscape, which could have implications for public health and healthcare systems.

The details

HMPV is transmitted through close contact with infected individuals or by touching contaminated surfaces. It typically spreads and is more durable in colder temperatures, with cases commonly starting to show up in January before peaking in March or April and then tailing off in June. However, the COVID-19 pandemic disrupted this seasonal trend, as people stayed home and developed less natural immunity to the virus. Now, as people have resumed normal activities, they are more vulnerable to HMPV infection.

  • HMPV cases commonly start showing up in January.
  • HMPV cases typically peak in March or April.
  • HMPV cases typically taper off in June.

The players

Dr. Neha Nanda

Chief of infectious diseases and hospital epidemiologist for Keck Medicine of USC.

Dr. Jessica August

Chief of infectious diseases at Kaiser Permanente Santa Rosa.

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What they’re saying

“That's why after the pandemic we saw record-breaking childhood viral illnesses because we lacked the usual immunity that we had, just from lack of exposure. All of that also led to longer viral seasons, more severe illness. But all of these things have settled down in many respects.”

— Dr. Jessica August, Chief of infectious diseases at Kaiser Permanente Santa Rosa

What’s next

Infectious-disease experts say the best way to avoid contracting HMPV is similar to preventing other respiratory illnesses, such as getting vaccinated, washing hands frequently, and wearing masks in crowded indoor settings.

The takeaway

While HMPV is not a new virus, its resurgence after the COVID-19 pandemic highlights the importance of maintaining vigilance and taking preventive measures against respiratory illnesses, even those without vaccines or specific treatments, to protect vulnerable populations and ensure the stability of public health and healthcare systems.