Chinese health authorities are reportedly seeing an increase in human metapneumovirus (HMPV) cases.

There is currently no evidence that the outbreak is exceptional or that a new respiratory virus or disease has emerged in China.

A spokesman for the World Health Organization (WHO) said data from China suggests that there has been a “recent increase in acute respiratory infections” but that “the overall extent and intensity of respiratory infections in China is lower this year than last.” Year”.

According to data from the Centers for Disease Control and Prevention (CDC), HMPV cases in the United States have increased steadily since November 2024, with 1.94% of weekly tests positive for HMPV as of December 28, 2024. In comparison, 18.71% of weekly tests in the same week were positive for flu and 7.10% were positive for COVID, the data shows.

In a statement Monday, the CDC said the agency is “monitoring reports of increased illness” in China as the country is reportedly grappling with a rising number of HMPV cases. The reports “do not present a cause for concern in the United States at this time,” the agency added.

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

“This is actually the winter season for respiratory viruses,” said Dr. William Schaffner, a professor of preventive medicine at Vanderbilt University Medical Center in Nashville, told ABC News. “All of these respiratory viruses — influenza, COVID, RSV, human metapneumovirus — are increasing this time of year, in part because we get so close to each other.”

“We are spending time indoors and of course all of these vacations, family gatherings and parties have been opportunities for us to get closer together and transmit the virus,” 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?

According to the CDC, HMPV is a virus that can cause upper and lower respiratory tract illnesses.

It was discovered in 2001 and is part of the Pneumoviridae family along with respiratory syncytial virus (RSV), according to the CDC.

According to the Federal Health Agency, there has been a better understanding and awareness of HMPV over the years, which has led to more widespread testing.

“Human metapneumovirus is another one of these respiratory viruses that we appreciate more now because we have the diagnostic capabilities to actually diagnose it more easily in hospitals, emergency rooms and even doctor’s offices,” Schaffner said. “Now we have diagnostic panels that can tell you whether you have influenza, COVID, RSV or human metapneumovirus.”

What are the symptoms?

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

Symptoms include cough, stuffy nose, fever and shortness of breath, the Federal Health Office said.

“It’s often indistinguishable from the other respiratory viruses because we don’t usually look for it unless someone is really sick,” says Dr. Peter Chin-Hong, a professor of medicine and infectious disease specialist at the University of California, San Francisco, told ABC News.

Young children and adults ages 65 and older are among those at highest risk of HMPV developing into bronchitis or pneumonia.

How does it spread?

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

As with other respiratory viruses, the U.S. typically sees a spike in HMPV cases in the winter and a decline in the spring.

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

Immunocompromised or elderly people may experience more severe symptoms if reinfection occurs.

Is there a treatment for HMPV?

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

“If you’re wheezing, we give bronchodilators,” Chin-Hong said, referring to a drug that relaxes and opens the airways and helps clear mucus from the lungs. “If you’re dehydrated, we give fluids; We bring down the fever.”

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

How do I prevent HMPV?

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

“People who are in that high-risk group for any of these viruses — particularly older people, frail people, people with weakened immune systems — if they are indoors where there are a lot of people, (they should) put their mask back on and think They also remember social distancing,” Schaffner said.

Chin-Hong and Schaffner added that it is important for people to receive vaccinations against other respiratory diseases such as COVID-19, flu and RSV.

Vaccination against other respiratory viruses can reduce the risk of co-infection and help doctors rule out certain diseases much earlier.

“Of course you can get serious illness 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 chance of co-infection.”

ABC News’ Youri Benadjaoud contributed to this report