What is human metapneumovirus and why are cases rising in China?

HMPV cases are rising in Asia, but experts advise to not panic

Author: Lauren J. Young edited by Dean Visser

Cases of a typical respiratory virus called human metapneumovirus (HMPV) are increasing. several Asian countriesbut experts say the situation shouldn’t raise concerns of a greater global health risk. HMPV is in the identical group of winter bugs as influenza and respiratory syncytial virus (RSV), which regularly peak presently of 12 months in the Northern Hemisphere. Common symptoms of HMPV, comparable to a runny nose, cough and fever, are often mild. However, the chance of severe disease could also be higher in young children, older adults and individuals with weakened immune systems.

In mid-December 2024, health agencies in China reported an overall increase in respiratory infections, including respiratory infections Increase in HMPV in children under 14 years of age in northern China. Reports of the hospital allegedly overflowing with cases have further fueled concern and attention for this lesser-known but common winter respiratory disease.

“There is quite a large outbreak in Asia – you might even call it an epidemic – of human metapneumovirus,” says William Schaffner, an infectious disease physician and professor at Vanderbilt University Medical Center. “There is no reason to panic. But for those at higher risk, this is the time to exercise caution. [to] be careful.”

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The relatively high variety of cases in China has prompted the country and nearby countries to extend surveillance. Cases have also been detected in Malaysia, India and Kazakhstan. Experts note that HMPV was occurring in humans nonetheless, around the globe for a long time.

“The virus has been circulating through at least 60 years oldand genetic evolution studies suggest that it diverged from the avian virus between 200 and 400 years ago,” says John Williams, a pediatrician and professor of infectious diseases on the University of Wisconsin–Madison who has been studying HMPV for greater than 20 years. “HMPV causes regular annual seasonal epidemics, similar to the more widely recognized influenza viruses and RSV. The typical HMPV season is in late winter and early spring. So it’s not completely unexpected.”

Williams says widespread population immunity should reduce the chance of a bigger public health problem. Schaffner adds that it’s likely that travelers in countries with high HMPV rates could “bring the virus to the United States, but it’s already here.”

Seasonal spikes occur yearly in the US. Currently reported by the US Centers for Disease Control and Prevention slight increase in HMPV in the country. However, case numbers are still low: In the week of December 28, almost 2 percent of diagnostic tests got here back positive for the virus. Last 12 months, HMPV peaked in April, with about 8 percent of tests returning positive results.

Scientific American spoke further with Schaffner about recent HMPV outbreaks, common symptoms, and who is most vulnerable to severe disease.

[An edited transcript of the interview follows.]

What is HMPV?

Human metapneumovirus is one other winter respiratory virus from the identical family as RSV that increases in numbers this time of 12 months [in the Northern Hemisphere]. The virus attacks our nose, throat and chest, so it is easily transmitted from individual to individual. Scientists have been taking a look at this virus for a while, but since it is not as significant as, for instance, the flu and COVID, it has not been as well-known to either the medical community or most people. It is also less known because we shouldn’t have easy and widely available diagnostics. But now hospitalized patients and even patients seen in doctor’s offices can receive diagnostic tests fairly quickly. That’s why doctors make this diagnosis more often than before. This virus has gained more attention, but it surely has at all times been there.

What are the symptoms?

Like other respiratory viruses, it may cause a stuffy nose, sore throat or cough since it enters the bronchial tubes. Some people may develop complications from pneumonia. We are most concerned about young children because they haven’t any experience with the virus or are not resistant to it, the elderly, frail, those affected by chronic diseases and those with weakened immune systems.

What will we know to this point about recent outbreaks and cases?

There is a pretty big epidemic in Asia – you may even call it an epidemic – of human metapneumovirus. It is diagnosed here in the USA. However, flu, COVID and RSV are now rather more commonly diagnosed. We can improve these diagnoses significantly, so the more we glance, the more we’ll find. I do not think this is something we needs to be concerned about. It’s definitely nothing nefarious. And yes, a few of these travelers [to countries with higher rates of HMPV] may bring the virus to the United States, but it surely is already here. I’m more concerned in regards to the US population with the flu that they’ve has increased over the previous couple of weeksand our hospitals and emergency rooms are just overflowing with individuals who are really miserable and seriously in poor health with the flu. The variety of cases of viral diseases and RSV is also increasing today.

Are there concerns a couple of larger-scale epidemic or pandemic?

I do not think we will call it a pandemic because there is nothing recent about this virus. Different parts of the world may develop at different times, but as they are saying, we are a worldwide village. And in fact, these viruses don’t need passports, in order that they can all travel around the globe and be introduced when people travel. And there was a whole lot of domestic travel in the U.S. through the holiday season; many individuals meet, family reunions, parties and the like. This created an environment for all of the respiratory viruses and accelerated their spread.

How to reduce the chance of HMPV infection?

We do not have a vaccine against human metapneumovirus, so the very best we will do is avoid individuals who are coughing and sneezing. If you get sick, don’t go to highschool or work. Stay at home. If you cough and sneeze, do it into your elbow. If you are going to an indoor space with many other people, wear a mask. If you actually are in a high-risk group, consider social distancing. Let’s wait until these viruses pass and then we will go outside. So social distancing and wearing a mask really helps, in addition to constant hand hygiene.