What Is Human Metapneumovirus, and Why Are Cases Rising in China?

HMPV cases are on the rise across Asia, but experts say not to panic

Who Lauren J. Young edited by Dean Visser

Cases of a common respiratory virus called human metapneumovirus, or HMPV, are on the rise several Asian countriesbut experts say the situation should not raise fears of a bigger global health threat. HMPV is included in the same mix as winter flu bugs respiratory syncytial virus (RSV), which often peak at this time of year in the Northern Hemisphere. Common symptoms of HMPV, such as runny nose, cough, and fever, are usually mild. However, young children, older adults, and immunocompromised individuals may be at greater risk of severe disease.

In mid-December 2024, Chinese health agencies reported a general increase in respiratory infections, among others. HMPV on the rise in children under 14 years of age in northern China. Reports of a hospital allegedly overwhelmed with cases raised alarm and increased attention to this little-known but common winter respiratory disease.

“In Asia, they’re having a fairly large outbreak of human metapneumovirus, you might call it an epidemic,” says William Schaffner, an infectious disease physician and professor at Vanderbilt University Medical Center. “There is no need to panic. But for people in higher-risk groups, it’s time to be careful, to be (cautious).”

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The relatively high number of cases in China has prompted the nation and neighboring countries to increase surveillance. Cases have also been detected in Malaysia, India and Kazakhstan. Experts say it was HMPV what happens in humans throughout the world for decades, however.

“The virus has circulated at least 60 years oldand genetic evolutionary studies suggest that it diverged from an avian virus between 200 and 400 years ago,” says John Williams, a pediatrician and professor of infectious diseases at the University of Wisconsin-Madison, who has studied HMPV for more than 20 years. “HMPV causes annual seasonal epidemics, similar to the more well-known influenza virus and RSV. The typical season for HMPV is from late winter to early spring. So this is not entirely unexpected.”

Williams says widespread population immunity should reduce the risk of a larger public health problem. Schaffner added that it’s plausible that travelers from countries with high rates of HMPV “bring the virus to the US, but it’s already here.”

The US experiences seasonal increases every year. The US Centers for Disease Control and Prevention reports today a small increase in the country’s HMPV. Cases are still low, however: in the week of December 28, almost 2 percent of diagnostic tests were positive for the virus. HMPV peaked in April last year, with about 8 percent of tests coming back positive.

American scientific He spoke with Schaffner more about recent outbreaks of HMPV, common symptoms and who is most vulnerable to serious illness.

(Below is an edited transcript of the interview.)

What is HMPV?

Human metapneumovirus is one of those winter respiratory viruses in the same family as RSV, and it increases this time of year (in the Northern Hemisphere). The virus affects the nose, throat and chest, so it is easily transmitted from person to person. Researchers have been studying this virus for some time, but because it does not have the prominence of influenza and COVID, for example, it has not been as well known to the medical community or the general public. The known is not so well known, because we have not had an easy and more comprehensive diagnosis. But now hospitalized patients, and even patients seen in doctors’ offices, can receive rapid diagnostic tests. Therefore, doctors make this diagnosis more often than before. This virus has received more attention, but it has always been there.

What are the symptoms?

Like other respiratory viruses, it can cause a stuffy nose, sore throat, or cough because it goes down into your bronchi. Some people may experience complications pneumonia. We are most concerned because young children have no experience or immunity to the virus, the elderly with underlying chronic illnesses, and the frail and immunocompromised.

What do we know so far about recent outbreaks and cases?

In Asia, there is a relatively large outbreak of the human metapneumovirus – it could even be called an epidemic. It’s being diagnosed here in the U.S. But at the moment, flu, COVID, and RSV are much more prominent today. We are much better able to make these diagnoses, so the harder we look, the more we find. I don’t think we need to worry about this. It’s certainly nothing evil. And yes, some of those travelers (to countries with higher HMPV rates) may bring the virus to the US, but it’s already here. I’m more concerned about the US population now with the flu, which it has has increased in recent weeksand our hospitals and emergency rooms are full of people who are very miserable and quite sick with the flu. And COVID and RSV are also on the rise today.

Are there concerns about a larger global outbreak or pandemic?

I don’t think we can call it a pandemic because there is nothing new about this virus. Different parts of the world may grow up at different times, but we are a global people, as the saying goes. And of course, these viruses don’t need a passport, so they can all move around the world and enter through the way humans travel. And here in the US there has been a tremendous amount of travel during the holiday season; gathering of many people, family reunions, parties and the like. This has provided an environment for all these respiratory viruses to accelerate their spread.

How can you reduce the risk of HMPV infection?

We don’t have a vaccine against human metapneumovirus, so what we can do is avoid people who are coughing and sneezing. If you get sick, please do not go to school or work. stay at home If you’re coughing and sneezing, do so into your elbow. If you are going indoors where there are many other people, wear a mask. If you’re in that really high-risk group, consider social distancing. Let’s wait for these viruses to pass, and then we can go outside. So social distancing and wearing a mask really helps, along with good hand hygiene.