A LITTLE-KNOWN VIRUS IS SPREADING IN NORTHERN CALIFORNIA. HERE'S WHAT TO KNOW
In offices and classrooms across the Bay Area, sick days are piling up again.
But many people testing negative for COVID-19 and the flu may be dealing with something else: a respiratory virus many Americans have likely never heard of - human metapneumovirus, or HMPV.
The virus isn't new. Scientists first identified it in 2001, and it circulates seasonally in the United States, typically from winter through spring, according to the Centers for Disease Control and Prevention.
This year, surveillance data and wastewater monitoring suggest HMPV is spreading widely in parts of Northern California, including in San Francisco and parts of the Bay Area.
The virus can be hard to spot because its symptoms closely resemble those of other respiratory illnesses.
At UC Davis Health, Dean Blumberg, chief of pediatric infectious diseases, said HMPV often looks similar to RSV.
"This includes upper respiratory symptoms that sometimes progress to pneumonia or bronchiolitis and wheezing," he said.
Here's what to know about the virus.
What is human metapneumovirus (HMPV)?
Human metapneumovirus is a respiratory virus that can cause both upper and lower respiratory illness in people of all ages, according to the CDC. It belongs to the same virus family as respiratory syncytial virus, or RSV.
Is HMPV spreading in Northern California?
Wastewater monitoring has detected elevated levels of HMPV in several Northern California communities, including San Francisco, Sacramento, Davis and Vallejo, according to data from WastewaterSCAN, a national wastewater surveillance program.
Wastewater testing can help track the spread of viruses in communities even when individuals are not tested.
Why are people hearing about HMPV now?
HMPV has circulated for decades but is less widely known than flu, COVID-19 or RSV.
Because its symptoms are nearly indistinguishable from other respiratory infections, many cases likely go undiagnosed, according to public health experts.
Increased monitoring of respiratory viruses since the COVID-19 pandemic has also brought greater attention to viruses such as HMPV.
What are the symptoms of HMPV?
Symptoms commonly include:
- Cough
- Fever
- Nasal congestion
- Sore throat
- Shortness of breath
In some cases, particularly among vulnerable patients, infection can progress to bronchitis or pneumonia, according to the CDC.
Who is most at risk of severe illness?
Most infections are mild, but some groups face a higher risk of complications.
According to the CDC, higher-risk groups include:
- Infants and children younger than 2
- Adults 65 and older
- People with weakened immune systems
- People with underlying lung or heart conditions
How does HMPV spread?
HMPV spreads in similar ways to other respiratory viruses.
- The CDC says transmission can occur through:
- Respiratory droplets from coughing or sneezing
- Close personal contact such as touching or shaking hands
- Touching contaminated surfaces and then touching the mouth, nose or eyes
Is there a vaccine or treatment for HMPV?
There is currently no vaccine and no specific antiviral treatment for HMPV, according to the CDC.
Treatment generally focuses on relieving symptoms. Most people recover on their own with rest, fluids and supportive care.
How can you reduce the risk of infection?
Public health experts recommend many of the same precautions used to prevent other respiratory illnesses:
- Wash hands frequently
- Cover coughs and sneezes
- Clean frequently touched surfaces
- Improve ventilation in indoor spaces
- Stay home when sick
When should someone seek medical care?
UC Davis Health advises contacting a doctor if symptoms become severe or unusual.
Warning signs may include:
- Difficulty breathing
- Chest pain
- Trouble staying hydrated
- Symptoms lasting longer than 10 days
- Fever or unusual lethargy in infants younger than 3 months
Related Reading
Subscribe
There’s more to San Francisco with the Chronicle. Subscribe today for just 25¢. 2026-03-10T01:03:44Z