Respiratory Virus That Lacks Vaccine Spreads in US

A little-known respiratory virus with no vaccine or specific treatment to combat it is surfacing in parts of the US, including California and New Jersey. Human metapneumovirus can infect both the upper and lower respiratory tract, the Centers for Disease Control and Prevention says, and care is limited to easing symptoms. Most people recover from HMPV without medical intervention, but health officials recommend rest, fluids, and staying home while sick, USA Today reports. In more serious cases, such as when breathing becomes difficult, oxygen therapy may be employed, according to the Cleveland Clinic.

The virus was first identified in 2001 and last saw a notable US surge in April 2025. As of Feb. 21, HMPV accounted for just over 5% of weekly positive respiratory virus tests, up from 3.83% the week before, federal surveillance data show; it peaked at 7.43% in April 2025. Cases have been increasing since October, per the Independent. Elevated levels are showing up in the San Francisco Bay Area and the Napa wine country, as well as the Northeast. China has dealt with the virus recently, too.

Health officials aren't alarmed at this point, per the Los Angeles Times: According to the Mayo Clinic, almost everyone will catch an HMPV strain at least once. Symptoms include cough, stuffy nose, fever, and shortness of breath, which can sometimes progress to bronchitis or pneumonia. Like flu, per USA Today, HMPV tends to circulate from winter into spring, with an incubation period of three to six days. Children and adults 65 and older face the highest risk of severe illness. Prevention relies on familiar steps: frequent handwashing, avoiding touching your face with unwashed hands, staying away from people who are sick, cleaning high-touch surfaces, improving indoor air quality where possible, and covering coughs and sneezes.