The human metapneumovirus (HMPV) is spreading in the United States, including in California and the Great Lakes region, according to the Centers for Disease Control and Prevention.

Symptoms include cough, fever, and nasal congestion, and, unlike better-known respiratory viruses, HMPV does not have a vaccine or known treatments, the CDC stated.

“There’s no specific treatment that’s generally recommended,” Dr. Dean Blumberg, chief of pediatric infectious diseases at the University of California–Davis Children’s Hospital, said in a video released by the school.

“For the youngest children, using a bulb syringe to clear the congestion can be useful. Sometimes a humidifier or vaporizer may be useful, especially if they have something like croup as a complication of infection and trying to make sure that they don’t get dehydrated and get enough fluids.”

Hospitalized patients typically receive supportive care, or oxygen if they need it, and intravenous fluids to prevent or treat dehydration.

Of nationwide tests that were positive for respiratory viruses in the week that ended on Feb. 28, 5 percent tested positive for HMPV—the highest percentage for HMPV since mid-2025. The percentage is lower than that of influenza and respiratory syncytial virus (RSV) but higher than that of COVID-19, according to the National Respiratory and Enteric Virus Surveillance System.

California and New Jersey are among the states that have recently reported HMPV cases. According to the CDC, cases have been recorded in all regions of the country.

Data voluntarily reported to the California Department of Public Health from clinical laboratories show an increase in HMPV test positivity to 8.6 percent during the week that ended on Feb. 28, a spokesperson for the department told The Epoch Times in an email on March 10.

The HMPV levels in California at this point are higher than during four of the past five respiratory virus seasons. The seasons run from the fall into the following year.

“While levels are currently higher than previous seasons, HMPV most commonly causes mild respiratory illness in people of all ages,” the spokesperson said. “Severe illness is less common. However, it can occur in young children, older adults, those with chronic medical conditions, and people with weakened immune systems.”

Blumberg also stated that symptoms are usually mild but that the virus can lead to more severe complications, particularly in young children, the elderly, and others with weaker immune systems.

HMPV usually starts circulating later in the season than influenza and RSV, researchers with the University of Pittsburgh School of Public Health and other institutions said in a study published in February.

They found that the virus also peaks later, often in April.

The researchers said that the study shows that HMPV was “an important cause” of respiratory symptoms among both children and adults.

Experts recommend practicing good hygiene during the virus season to prevent HMPV and other viruses, including covering one’s mouth when coughing or sneezing and frequently washing one’s hands.