Rising HMPV cases in China are 'what we would expect to see' in winter, health officials say

This winter, China has seen an increase in respiratory infection cases, with a little-known virus drawing widespread attention. Concerns have arisen about whether the increase in cases could have broader global implications.

Human metapneumovirus (HMPV) can cause upper and lower respiratory illnesses in people of all ages. Data released last week by the Chinese Center for Disease Control and Prevention showed an increase in cases in China in recent weeks. However, HMPV typically circulates during the winter in the Northern Hemisphere. The Chinese CDC data also showed increases in other common respiratory infections, including seasonal influenza and respiratory syncytial virus (RSV).

World Health Organization spokesperson Margaret Harris stated at a press briefing on Tuesday, “The levels of respiratory infections reported by China are within the normal range. This is what we would expect to see in winter.” To alleviate concerns, she added that China's current hospitalization rates are lower than they were at the same time last year, and the country has not initiated any emergency declarations or emergency responses due to these respiratory infections. Harris also emphasized, "Regarding human metapneumovirus, it is not a new virus."

Harris explained, “It was first identified in 2001. It has been circulating in the population for a long time. It is a common virus, circulating during the winter and spring.” In the United States, the CDC tracks HMPV cases in the same way it tracks the spread of other respiratory viruses. It is estimated that HMPV causes about 10% to 12% of respiratory illnesses in children; most people will contract HMPV before the age of 5 and may get it again throughout their lives.

Data shows that HMPV cases began to appear more frequently in November and have been increasing since then. However, compared to other common viruses, the percentage of weekly respiratory infection tests that were positive for HMPV was low at 1.94% as of December 28. In comparison, influenza was 18.71% and COVID-19 was 7.10% for the same week. Janet Hamilton, executive director of the Council of State and Territorial Epidemiologists, said, “There’s a reason why there’s a respiratory virus season. We’ve gotten very used to thinking about those really big viruses—like COVID, flu, and RSV—but there are a lot of other respiratory viruses that can make you sick.”

Hamilton said that for common respiratory infections like HMPV, “a lot of times, you’re going to get better on your own, but not always.” She added, “Typically, the infections are relatively mild, and we usually think of it like a common cold.” “A lot of people don’t necessarily know that they have a common cold caused by human metapneumovirus, but it’s definitely one of the viruses that is frequently associated with the common cold.” Common symptoms associated with HMPV infection include cough, fever, nasal congestion, and shortness of breath.

HMPV spreads similarly to some other respiratory viruses: through droplets produced by coughing or sneezing and through touch, such as shaking hands or touching contaminated surfaces. Harris said, “Simple measures can prevent transmission. These measures include, if you are sick, if you have symptoms, stay home.” “Also, if you’re in crowded or poorly ventilated spaces, when you know there are viruses circulating, consider wearing a mask. Improve ventilation where possible.” She also added, “Of course, cover your coughs and sneezes with a tissue.”

Harris stated that some people are at higher risk of developing severe illness from HMPV infection. “In some cases, like any common cold virus, it can cause more severe disease in people who have no immunity or who have a very weak immune system,” she said. “That is the very young. That is newborn babies—that’s why you don’t go visit a newborn baby and kiss it when you have a cold—and the very elderly. Again, that’s why you shouldn’t visit your 90-something-year-old great-grandmother in the hospital when you have a cold.”

Healthcare providers can test for HMPV, but there is currently no vaccine, nor is there a specific antiviral therapy to treat the infection. Resting at home and staying hydrated can help relieve symptoms, as can some over-the-counter medications. Mild cases of HMPV typically last a few days to a week, with many people recovering on their own within two to five days. John Tregoning, a professor of vaccine immunology at Imperial College London, said in a statement released by the UK Science Media Centre on Monday, “It will present in the same way as flu, COVID, RSV, so the advice for people affected is the same – rest, hydrate, try not to spread it to others.” He also said, “If you’re feeling really unwell, see your GP.” “As it’s a virus, antibiotics won’t have any effect.”