China is experiencing an uptick in cases of human metapneumovirus (HMPV), prompting health officials to closely monitor the situation. While the rise in cases has drawn attention, the World Health Organization (WHO) has clarified that the outbreak appears routine and does not indicate the emergence of a new virus or illness.
According to the WHO, recent data from China shows an increase in acute respiratory infections, but the overall scale of respiratory illnesses this year remains lower than in 2023. In the United States, HMPV cases have also been on the rise since November 2024, with 1.94% of weekly tests returning positive for the virus as of late December. For comparison, influenza accounted for 18.71% of positive tests, while COVID-19 registered at 7.10% during the same period, according to data from the Centers for Disease Control and Prevention (CDC).
Despite the uptick, the CDC has stated that reports from China are “not currently a cause for concern in the U.S.” Public health experts emphasize that HMPV is well-known and typically peaks during the winter respiratory virus season.
Discovered in 2001, human metapneumovirus is part of the Pneumoviridae family, which also includes respiratory syncytial virus (RSV). The virus can cause upper and lower respiratory infections and has become increasingly recognized due to advances in diagnostic tools.
“Human metapneumovirus is one of those respiratory viruses we’re appreciating more as diagnostic capabilities improve,” said Dr. William Schaffner, a professor of preventive medicine at Vanderbilt University Medical Center. “Now we can readily diagnose it in hospitals, emergency rooms, and even physician offices using advanced diagnostic panels.”
The incubation period for HMPV is three to six days. Symptoms include cough, nasal congestion, fever, and shortness of breath.
“It’s often indistinguishable from other respiratory viruses unless specifically tested for,” explained Dr. Peter Chin-Hong, an infectious diseases expert at the University of California, San Francisco. While the virus generally causes mild symptoms, it can lead to bronchitis or pneumonia in young children, older adults, and immunocompromised individuals.
HMPV spreads through respiratory secretions, such as those from coughing and sneezing, as well as through close personal contact or touching contaminated surfaces. Like other respiratory viruses, HMPV cases in the U.S. typically peak during the winter months and decline in the spring.
Most people are exposed to HMPV by the age of five. Although reinfections can occur, symptoms are generally milder in subsequent infections, except for high-risk groups such as older adults and those with weakened immune systems.
Currently, there are no antiviral treatments specifically for HMPV. Supportive care is the primary approach, which may include bronchodilators to alleviate wheezing and open airways, fluids to combat dehydration, and medications to reduce fever. Antibiotics may be prescribed if a bacterial co-infection develops.
“Treatment focuses on relieving symptoms and managing complications,” said Chin-Hong.
Since there is no vaccine for HMPV, prevention relies on good hygiene practices, including washing hands regularly with soap and water, covering the mouth and nose when coughing or sneezing, and staying home when feeling unwell. High-risk individuals are advised to take extra precautions, such as wearing masks in crowded indoor spaces and maintaining social distance. Vaccinations for other respiratory viruses, including flu, COVID-19, and RSV, can also help reduce the risk of co-infections, which can complicate HMPV cases.
“If you contract HMPV along with another respiratory infection like influenza or pneumococcus, the outcomes could be more severe,” noted Chin-Hong. “Vaccinations can help minimize those risks.”
Public health experts attribute the increase in HMPV cases to seasonal factors, including winter weather, indoor gatherings, and holiday travel.
“During winter, respiratory viruses thrive as people spend more time indoors and nearby,” said Schaffner. Improved diagnostic testing has also contributed to identifying more cases, shedding light on the virus’s prevalence.
While the rise in HMPV cases in China has drawn attention, health officials stress that it is not unusual for respiratory viruses to fluctuate in severity and prevalence. The WHO continues to monitor the situation but has not flagged any new risks.
In the U.S., the CDC is observing the trends but remains confident that the current rise in HMPV cases does not pose a significant public health threat.
Understanding and recognizing HMPV is crucial, especially during the winter respiratory virus season. While the virus is not a cause for widespread alarm, following preventive measures and seeking medical care when needed can help mitigate its impact.
HMPV underscores the importance of vigilance during respiratory virus season. By staying informed and proactive, individuals can protect themselves and others from this and other respiratory infections.
