Human Metapneumovirus Spreading in Northern California: What You Need to Know

A respiratory virus without a specific vaccine or treatment is circulating in parts of California, particularly Northern California. While public health officials advise against alarm, understanding the virus – human metapneumovirus (HMPV) – is crucial as it resurges after being suppressed during the COVID-19 pandemic.

What is HMPV?

Human metapneumovirus (HMPV) was first detected in 2001, according to the U.S. Centers for Disease Control and Prevention. It spreads through close contact with infected individuals or by touching contaminated surfaces.

Like other respiratory illnesses, such as influenza, HMPV thrives in colder temperatures. Typically, HMPV cases begin appearing in January, peak in March or April, and decline by June.

Why is HMPV Resurging Now?

Prior to the 2020 pandemic, regular exposure to seasonal viruses like HMPV provided Americans with a degree of natural immunity. This protection diminished as people isolated themselves during the pandemic. As normal activities resumed, individuals became more susceptible to the virus.

Unlike some other respiratory viruses, there is currently no vaccine available for HMPV.

Where is HMPV Spreading in California?

Wastewater surveillance data indicates high concentrations of HMPV in several Northern California communities. Specifically, Merced, Novato, and Sunnyvale in the San Francisco Bay Area have seen increases in HMPV levels in wastewater between mid-December and the finish of February. HMPV has also been detected in Los Angeles County, though at lower levels. Additional areas affected include San Francisco, Marin, Vallejo, Napa, Santa Rosa, Sacramento, and Davis.

What are the Symptoms of HMPV?

HMPV typically causes mild, cold-like symptoms, including cough, fever, nasal congestion, and sore throat.

In some cases, HMPV infection can lead to:

• Asthma attacks and reactive airway disease (wheezing and difficulty breathing)
• Middle ear infections
• Croup (a “barking” cough)

While anyone can contract HMPV, those who are immunocompromised or have underlying medical conditions are at higher risk of severe illness, including pneumonia. Young children and older adults are also considered high-risk groups.

How is HMPV Treated?

Currently, there is no specific treatment protocol or antiviral medication for HMPV. Treatment focuses on managing symptoms with rest and fluids. If symptoms worsen, consulting a healthcare provider is recommended.

How to Prevent HMPV

Preventative measures for HMPV are similar to those for other respiratory illnesses:

• Wash your hands frequently with soap and water, or use an alcohol-based hand sanitizer.
• Clean frequently touched surfaces.
• Improve air flow in crowded spaces.
• Avoid close contact with sick individuals.
• Avoid touching your eyes, nose, and mouth.