WASHINGTON – A respiratory virus, human metapneumovirus (HMPV), is currently spreading rapidly across the United States, prompting increased monitoring from health officials. While typically causing mild illness, HMPV poses a greater risk to infants, older adults, and individuals with weakened immune systems, and currently lacks a specific vaccine or antiviral treatment.
The Centers for Disease Control and Prevention (CDC) reported that HMPV accounted for approximately 5% of positive respiratory tests nationwide in early March 2026, a rise from 3.8% in late February. This increase, first noted in the fall of 2025, has drawn attention as the virus can mimic common respiratory illnesses like the cold and flu, making diagnosis difficult without testing.
Discovered in 2001, HMPV belongs to the Pneumoviridae family, the same family as respiratory syncytial virus (RSV). According to the CDC, the virus spreads through respiratory droplets produced when an infected person coughs or sneezes, as well as through close contact like handshakes or by touching contaminated surfaces and then touching the face.
While most HMPV infections are mild, symptoms can include cough, fever, nasal congestion, and shortness of breath. In some cases, the infection can progress to bronchitis or pneumonia, particularly in vulnerable populations. Dean Blumberg, chief of pediatric infectious diseases at UC Davis Health, noted that HMPV causes symptoms “very similar to RSV,” and can lead to bronchiolitis and wheezing, especially in children under two years of age. Infants born prematurely, or those with pre-existing heart or lung conditions, are at higher risk of severe illness.
Health officials are advising preventative measures such as frequent handwashing, cleaning surfaces, and staying home when sick. Individuals experiencing severe symptoms, such as difficulty breathing or chest pain, are urged to seek medical attention. The CDC notes that most people can recover at home with rest and fluids.
Wastewater surveillance data indicates high levels of HMPV in Northern California, including Sacramento, Davis, Vallejo, and San Francisco, according to UC Davis Health. The virus is seasonal, typically peaking during winter through spring, but cases are currently rising across the U.S., including in Region 9, which encompasses California, Nevada, Arizona, and Hawaii.
In adults, HMPV infection may complicate chronic obstructive pulmonary disease (COPD), and pneumonia can occur in older adults and those with compromised immune systems. Health authorities continue to monitor the spread of HMPV and its potential impact on healthcare systems.
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