Viral disease HMPV is on the rise among kids in China — what is it?

Editor's note: This is an emerging story and will be updated.

A viral infection called human metapneumovirus (HMPV) is on the rise among children in China, according to Chinese state media.

The virus can cause upper respiratory tract infections — like colds — as well as serious lung infections and, according to state media, it's now one of the top four most common viral infections among hospital visitors in China.

"HMPV has been recognised as a significant problem in the at-risk population across the world since the turn of the century when it was first discovered," Andrew Easton, a virology professor at the University of Warwick in the U.K. who studies pneumoviruses, told Live Science in an email. "That risk has not changed significantly over the last almost 25 years."

That said, "it is always concerning to see a change in the incidence or pattern of an infection," Easton added. It's important to investigate potential surges in infection to pinpoint their cause.

What is HMPV?

HMPV belongs to the same family of viruses as respiratory syncytial virus (RSV), a seasonal virus that also causes colds and lung infections. HMPV was discovered in 2001 and, according to the U.S. Centers for Disease Control and Prevention (CDC) epidemiologist Eileen Schneider, the virus is associated with approximately 20,000 hospitalizations among children under 5 in the U.S. every year.

Common symptoms of the infection include cough, fever, a blocked nose and shortness of breath. However, these can progress to bronchitis (inflammation of the air tube leading to the lungs) or pneumonia (where the lungs' air sacs fill with fluid).

Young children, the elderly and those with compromised immune systems are most vulnerable to severe symptoms, according to the CDC.

Related: Who should get the new RSV vaccines? Here's everything you need to know

Should other countries be worried about HMPV in China?

"HMPV is a serious concern especially for very young infants in the first year of life," Easton said. This is also true of RSV, as well as seasonal influenza, or "the flu." However, he added that the risk posed by HMPV has not significantly changed since its discovery in the early 2000s.

In a statement released Dec. 27, Kan Biao, the head of the China CDC's National Institute for Communicable Disease Control and Prevention, announced that the rate of HMPV among children ages 14 and under was on the rise in China, according to China Daily. This rise in cases was also reported by Reuters. However, the scale and cause of the uptick are still unclear.

"It is important to be able to detect changes in patterns of infection and to then identify what the potential causes are," Easton said. "[We must] assess whether it is a change in a behavior of the infected people that has led to increased exposure or whether it is a change in the virus that has led to increased numbers of infected individuals."

It's unlikely that mutations, or genetic changes, to the HMPV virus are the culprit behind the reported rise in infections, he said, but additional testing of the virus's genetic code is required to rule out this possibility.

Meanwhile, China Daily noted that the overall spread of respiratory infections in China this winter has been lower than in recent years.

Live Science has reached out to officials and scientists in China for comment on the situation but had not heard back at the time of publication.

How can we protect ourselves from HMPV?

There are no available vaccines against HMPV. Additionally, according to the U.S. CDC, there are no specific antiviral treatments for the virus. Rather, treatment for HMPV is supportive, meaning it aims to reduce symptoms and keep vital signs stable.

According to the CDC, the infection duration is variable between individuals but similar to other respiratory infections, including the common cold.

To prevent HMPV infections, individuals can take the same precautionary measures they would for other respiratory viruses.

"HMPV is a respiratory infection spread in the same way as other respiratory viruses like flu and COVID-19," Easton said. "We can protect ourselves against HMPV in the same way that we do for those viruses."

The CDC recommends the following:

• Regularly wash hands with soap and water for at least 20 seconds
• Avoid touching eyes, nose and mouth with unwashed hands
• Avoid close contact with people who are unwell
• Cover your mouth when coughing and sneezing
• Stay at home when sick

HMPV is among the viral illnesses that the U.S. CDC monitors continually, so any uptick in infection would become apparent very quickly.