A virus without a vaccine is spiking throughout California. Here’s what doctors say you need to know
Doctors are warning people to be careful because of the seasonal flu virus, which can spread pneumonia and bronchitis in California’s wastewater and across the country.
high levels human metapneumovirus The virus, also known as HMPV, has been detected in dozens of Northern California cities, according to the public WastewaterScan Dashboard database.
The highest levels were reported in Redwood City. according to control panel. High levels were also found San Francisco Bay Area and Napa’s Wine Country.
HMPV levels remain lower in other parts of the country. A map on the dashboard shows HMPV levels are highest in California and along the Northeast coast.
According to data, cases across the country have been increasing since October 2025. Centers for Disease Control and Prevention. HMPV usually wanders in winter and springThe agency states:
High levels of human metapneumovirus circulate in California wastewater. Cases have been increasing in the US since October 2025 (Getty Images)
Mayo Clinic Clinical Virology Laboratory Director Dr. “In late winter and early spring, it can account for five percent to 10 percent of all respiratory infections that we diagnose in the United States. So it’s definitely there,” says Matthew Binnicker. It was previously announced.
Infectious diseases specialist at UC San Francisco, Dr. Monica Gandhi said that with a quieter Covid season, “other viruses like flu and HMPV are also getting their chance.” SFGate When asked about the state’s cases.
Viruses are “competing with each other,” he said. “When we had big surges in Covid, we saw that the rates of other cold viruses were really low.”
HMPV infection typically causes cold-like symptoms that last only a few days to a week. But experts warn that it can also lead to more serious symptoms, such as middle ear infections, life-threatening asthma attacks and a barking cough.
D., professor and Medical Director of Infectious Diseases at UNC Health. “The most important symptoms are cough, runny nose, and fever. You’re also prone to some wheezing, especially if you have underlying asthma,” said David Weber. WTVD in North Carolina.
In rare cases, infection can result in death in more vulnerable patients; babies, old and people who are immunocompromisedResearchers say.
The same is true for other respiratory viruses that spread across the country, such as influenza and RSV.
Unlike influenza and RSV, there is no vaccine to prevent HMPV infections diagnosed through laboratory tests.
According to the report, almost everyone will be infected with at least one type of HMPV in their lifetime. Mayo Clinic. If you’re over five years old, you’ve probably experienced this at least once. Cleveland Clinic notes.
Among U.S. adults, an estimated 12 hospitalizations per 100,000 people occurred each year from 2016 to 2019. 2025 report showed.
A chart from the Centers for Disease Control and Prevention shows weekly HMPV tests positive in the U.S. from 2024 through this month (CDC)
Most people will recover with rest and hydration, and Weber says over-the-counter medications can relieve symptoms.
A hospital may give patients an oxygen mask, steroids to reduce inflammation causing symptoms, or fluids in an IV to prevent symptoms from worsening, according to the Cleveland Clinic.
Respiratory virus can spread through direct contact, sneezing, coughing, or touching infected surfaces.
To prevent infection, the CDC recommends that people wash their hands regularly with soap, clean surfaces, and stay home if they feel unwell.
HMPV was discovered in 2001, but studies have shown that the virus Circulating since the 1970s.
