The human metapneumovirusalso known as HMPV, is reportedly on the rise in China, raising questions about what the disease is and whether it is a concern in the US

Chinese health officials have not confirmed that HMPV is driving the country’s hospitalizations, and recent reports from the Chinese Center for Disease Control and Prevention indicate that the increase may actually be due to influenza A. But with less publicity about HMPV in the U.S., concerns about a possible new pandemic have grown — even though experts say there’s no need for alarm.

“Pandemic concerns may subside,” Ph.D. Carla Garcia Carreno, Children’s Medical Center Plano director of infection prevention and control, told CBS News, adding that not only is the virus fairly stable, but it’s also not a new virus like COVID-19 was. “This has been circulating for some time, so people have some immunity against this human metapneumovirus.”

What is HMPV?

HMPV is a virus that can cause upper and lower respiratory tract diseases in people of all ages. Young children, older adults and people with weakened immune systems are at greatest risk of serious illness caused by the virus.

The length of the illness varies depending on the severity of the individual case, but is similar to other respiratory infections caused by viruses, according to the Centers for Disease Control and Prevention.

symptoms of HMPV

According to the CDC, symptoms commonly associated with HMPV include:

• Cough
• Fever
• Nasal congestion
• Shortness of breath

“Clinical symptoms of HMPV infection can progress to bronchitis or pneumonia and are similar to other viruses that cause upper and lower respiratory tract infections,” according to the CDC website.

Is HMPV a new virus?

HMPV is not new. It was first discovered in 2001 and is part of the Pneumoviridae family along with respiratory syncytial virus, or RSVAccording to the CDC.

It may have circulated earlier — for decades or more than a century, Garcia Carreno said.

In the U.S., HMPV usually circulates in the winter and lasts until or through the spring, the CDC says, and can circulate at the same time as RSV and influenza during respiratory virus season.

Is HMPV worse than COVID?

Experts say the HMPV outbreak in China is not a major concern — it is neither a new, mysterious disease nor is it responsible for as many cases as COVID or other infections even this season. According to the latest CDC data, HMPV accounts for less than 2% weekly positive tests for respiratory viruses. In comparison, the flu accounted for almost 19% and COVID for just over 7% in the same week.

For the disease to be considered locally widespread, there must be above 10% positive results over two weeks. At 1.9%, Garcia Carreno said it’s nowhere near the number of flu, COVID and RSV cases.

Researchers estimate that about 10% to 12% of respiratory illnesses in children are caused by HMPV, according to the Cleveland Clinic.

“Most cases are mild, but about 5% to 16% of children will develop a lower respiratory tract infection such as pneumonia,” the clinic’s website adds.

HMPV transmission and prevention

HMPV is spread by direct contact with someone who has it or by touching objects infected with the virus.

“Unfortunately, compared to influenza, RSV and COVID, we don’t have a vaccine for human metapneumovirus, so we don’t have that advantage in preparing or boosting our immune system to fight these viruses,” Garcia Carreno said. “But still, everything else we’ve learned about COVID can be applied to methane.”

To prevent illness, take similar steps as you would to prevent other respiratory viruses, which means washing your hands with soap and water and avoiding close contact with sick people.

“If someone is sick, try to avoid crowds so as not to expose everyone, especially vulnerable people,” Garcia Carreno said. “If that person is sick and can’t avoid going to a place where other people are, then try to use a mask, follow the rules of behavior when coughing and sneezing, and wash your hands well.”