Northern California is experiencing a surge in respiratory illness, but this isn’t another wave of COVID-19 or the seasonal flu. Instead, a less familiar virus – human metapneumovirus, or HMPV – is circulating widely, leading to empty offices and increased doctor’s visits. Concentrations of the virus are particularly high in several Bay Area communities, according to recent data.
Wastewater surveillance, a growing public health tool, has revealed elevated levels of HMPV in San Francisco, Marin, Vallejo, Napa, Novato, Santa Rosa, Sacramento, and Davis. This data, collected by WastewaterSCAN, indicates a significant increase in the virus’s presence in these areas. Even as HMPV typically circulates during the winter and spring months, its current prevalence is raising concerns among health officials.
What is Human Metapneumovirus?
Human metapneumovirus (HMPV) is a common respiratory virus that can cause illness similar to a cold, but can as well lead to more serious respiratory infections. The Centers for Disease Control and Prevention (CDC) explains that while most infections are mild, particularly in healthy children, HMPV can cause bronchiolitis – an infection of the small airways in the lungs – and croup, characterized by a distinctive “barking” cough. The Mayo Clinic describes this cough as sounding similar to a seal’s bark, and it’s most common in young children.
Why is HMPV Surging Now?
The rise in HMPV cases comes as COVID-19 levels remain relatively low. Dr. Monica Gandhi, an infectious disease specialist at UC San Francisco, explained that viruses often “compete” with each other. “When we had big COVID surges, we saw really low rates of other common cold viruses,” she said, according to SFGATE. With COVID-19 activity quieter this season, other respiratory viruses, like influenza and HMPV, are finding more opportunities to spread.
Symptoms and Transmission
HMPV symptoms are similar to those of other respiratory illnesses, including cough, fever, congestion, and sore throat. The virus spreads through respiratory droplets produced when an infected person coughs or sneezes, as well as through contact with contaminated surfaces. Transmission can also occur through direct contact, such as shaking hands with someone who is sick.
HMPV Across the United States
The increase in HMPV isn’t limited to Northern California. Data from the CDC and WastewaterSCAN show an upward trend of the virus throughout the U.S., with the Midwest and Northeast currently experiencing the highest rates. HMPV is an RNA virus, which, like COVID-19, tends to thrive in colder environments. Crowded indoor spaces facilitate its spread, though Dr. Gandhi notes that California’s milder weather and emphasis on ventilation may offer some protection.
Prevention and Treatment
Currently, there are no specific vaccines or treatments for HMPV. The CDC recommends standard preventative measures to slow the spread of the virus: stay home if you are sick, wash your hands frequently, and regularly clean surfaces. Most people recover from HMPV infection with rest, fluids, and supportive care.
What to Expect Next
Health officials continue to monitor HMPV levels through wastewater surveillance and clinical reporting. The CDC provides updated information on its website, and local health departments are tracking cases within their communities. As of March 3, 2026, the focus remains on mitigating spread through personal hygiene and staying home when ill.
This situation underscores the ongoing challenge of managing respiratory viruses and the importance of continued vigilance. If you are experiencing symptoms of a respiratory illness, consult with your healthcare provider for guidance.
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Disclaimer: This article provides general information about human metapneumovirus and should not be considered medical advice. Always consult with a qualified healthcare professional for diagnosis and treatment of any medical condition.
