Cases of a common respiratory virus known as human metapneumovirus, or HMPV, are increasing in several Asian nations, but doctors believe the situation should not raise concerns about a bigger global health danger. HMPV belongs to the same category of winter bugs as influenza and respiratory syncytial virus (RSV), which frequently peak around this time of year in the Northern Hemisphere. HMPV symptoms, including a runny nose, coughing, and fever, are usually minor. However, young children, the elderly, and those who are immunocompromised may be more vulnerable to serious diseases.
In mid-December 2024, Chinese health organizations reported an overall increase in respiratory illnesses, including an HMPV upsurge in children under the age of 14 in northern China. Reports of a hospital being overwhelmed with cases heightened concern and attention to this lesser-known but frequent winter respiratory ailment.
“In Asia, they are having a fairly large outbreak—might even call it an epidemic—of human metapneumovirus,” says William Schaffner, an infectious disease physician and a professor at Vanderbilt University Medical Center. “There’s no need to be panicky. But for those folks who are in higher-risk groups, this is a time to be careful, [to] be cautious.”
China’s unusually high case count has forced the country and neighbouring countries to step up monitoring. Cases have also been identified in Malaysia, India, and Kazakhstan. Experts point out that HMPV has been found in humans all across the world for decades.
“The virus has circulated for at least 60 years, and genetic evolutionary studies suggest that it diverged from a bird virus between 200 to 400 years ago,” says John Williams, paediatrician and infectious diseases professor at the University of Wisconsin–Madison, who has studied HMPV for more than 20 years. “HMPV causes regular annual seasonal epidemics, similar to the more widely recognized influenza virus and RSV. The typical HMPV season is late winter to early spring. So this is unexpected.”
Williams believes that extensive population immunity should reduce the risk of a greater public health concern. Schaffner adds that it’s possible that tourists in countries with high HMPV rates could “bring the virus to the U.S.—but it’s here already.”
The United States suffers seasonal surges every year. The United States Centers for Disease Control and Prevention now reported a small increase in HMPV throughout the country. However, cases remain low: as of the week of December 28, roughly 2% of diagnostic tests were positive for the virus. Last year, HMPV peaked in April, with approximately 8% of tests coming back positive.
