What you need to know about HMPV as China sees rise in cases

(CHINA) — Chinese health officials are reportedly monitoring an increase in cases of human metapneumovirus (HMPV).

There is currently no evidence that the outbreak is out of the ordinary or that a new respiratory virus or illness has emerged in China.

A spokesperson for the World Health Organization (WHO) said data from China indicates “there has been a recent rise in acute respiratory infections” but that “the overall scale and intensity of respiratory infectious diseases in China this year are lower than last year.”

Cases of HMPV have been steadily increasing in the U.S. since November 2024 with 1.94% of weekly tests positive for HMPV as of Dec. 28, 2024, according to data from the Centers for Disease Control and Prevention (CDC). By comparison, 18.71% of weekly tests were positive for flu and 7.10% were positive for COVID during the same week, the data shows.

Public health experts told ABC News that HMPV is well-known to health care professionals and commonly circulates during respiratory virus season.

“This is that winter respiratory virus season, indeed,” Dr. William Schaffner, a professor of preventive medicine at Vanderbilt University Medical Center in Nashville, told ABC News. “So, all of these respiratory viruses — influenza, COVID, RSV, human metapneumovirus — they all increase this time of the year, in part because we get so close to each other.”

“We spend time indoors and, of course, all of this holiday traveling, family get-together, and parties have been opportunities for us to get close together and for the virus to be transmitted,” he continued.

Here’s what you need to know about HMPV, including what it is, how it spreads and how to treat it.

What is HMPV?

HMPV is a virus that can cause upper and lower respiratory disease, according to the CDC.

It was discovered in 2001 and is in the Pneumoviridae family along with respiratory syncytial virus, or RSV, the CDC said.

Over the years, there has been a better understanding and awareness of HMPV, which has led to broader testing, according to the federal health agency.

“Human metapneumovirus is another one of those respiratory viruses that we’re now appreciating more because we have the diagnostic capability to actually diagnose it more readily in hospitals, emergency rooms and even in physicians’ offices,” Schaffner said. “Now we have diagnostic panels that can tell you whether you have influenza or COVID or RSV or human metapneumovirus.”

What are the symptoms?

HMPV has an incubation period of three to six days, according to the CDC.

Symptoms include cough, nasal congestion, fever and shortness of breath, the federal health agency said.

“It’s oftentimes indistinguishable from the other respiratory viruses, because we don’t usually check for it unless somebody is really ill,” Dr. Peter Chin-Hong, a professor of medicine and an infectious diseases specialist at the University of California, San Francisco, told ABC News.

Young children and adults aged 65 and older are among those at the highest risk of HMPV progressing to bronchitis or pneumonia.

How does it spread?

HMPV can spread through secretions from coughing and sneezing, close personal contact and touching objects that have the virus and then touching the eyes, nose or mouth, according to the CDC.

In the U.S., like other respiratory viruses, HMPV cases typically rise in the winter and decrease in the spring.

Chin-Hong said most people are exposed to HMPV by the time they’re five years old. People can get reinfected, but symptoms are typically milder.

Those who are immunocompromised or are older may experience more severe symptoms if they are reinfected.

Is there treatment for HMPV?

There are no antivirals to treat HMPV, so treatment consists of providing supportive care to patients with moderate or severe symptoms, the experts said.

“If you’re wheezing, we’ll give bronchodilators,” Chin-Hong said, referencing a medication that relaxes and opens the airways and helps clear mucus from the lungs. “If you’re dehydrated, we give fluid; we reduce the fever.”

Chin-Hong said that because people may develop co-infections, including bacterial infections, antibiotics may need to be given.

How do I prevent HMPV?

There is no vaccine to prevent HMPV, so prevention includes following basic hygiene including washing hands with soap and water, covering the nose and mouth when coughing and sneezing and staying home when sick.

“People who are in this high-risk group for any of these viruses — particularly older people, people who are frail, people who are immune-compromised — if they go indoors where there are a lot of people, [they should] put their mask back on and also consider social distancing,” Schaffner said.

Chin-Hong and Schaffner added that it’s important for people to receive vaccines for other respiratory illnesses including COVID-19, flu and RSV.

Getting vaccinated against other respiratory viruses can reduce the risk of co-infection and may help health care professionals rule out certain illnesses much sooner.

“Sure, you can get serious disease from HMPV itself, but if you get HMPV plus pneumococcus or HMPV plus influenza or RSV, it could be much worse,” Chim-Hong said. “During respiratory virus season, you want to minimize the probability of co-infection.”

ABC News’ Youri Benadjaoud contributed to this report