High levels of human metapneumovirus (HMPV) have been reported in parts of China. The news has sparked some concern, no doubt reminding people of a certain virus that erupted from this part of the world almost exactly five years ago. But do you really need to be worried about this latest disease outbreak? Here’s everything you need to know, featuring some expert commentary on the issue. 

What is HMPV?

HMPV is a single-stranded RNA virus of the family Pneumoviridae. There is currently no vaccine against the infection, although candidates are being developed by several teams of researchers, including a joint vaccine against both HMPV and the closely related respiratory syncytial virus (RSV). 

The virus causes cold- and flu-like respiratory symptoms, including fever, a cough, a runny or blocked nose, sore throat, and headaches. Most people experience relatively mild symptoms, although it can cause severe bronchiolitis and pneumonia in some cases.

It was first identified in 2001 among 28 young children in the Netherlands. Further study of the virus showed that “virtually all” children in the Netherlands have been exposed to human metapneumovirus by the age of 5 and that the virus had been circulating in humans for at least 50 years.

So, a key point: HMPV is not a novel virus that has suddenly emerged. This is very different from COVID-19, which emerged five years ago as a novel disease that had never infected humans before. 

HMPV is a frequent cause of “common cold” illnesses that kids catch all the time around the world. However, it’s estimated that the viral infection is responsible for around 10 percent of hospitalizations from lower respiratory tract infections.

So, if the virus is nothing new, what’s the big deal?

Why is HMPV in the news?

The Chinese Center for Disease Control and Prevention has reported that rates of multiple flu-like illnesses are on the rise in China, most notably HMPV, according to Newsweek. 

Statistics of the outbreak are elusive, but available datasets reportedly show that HMPV is the second-leading cause of respiratory infections among children in the country, second only to influenza, but ahead of other flu-like diseases, such as COVID-19, rhinovirus infection, and adenovirus infection.

“China is experiencing a large outbreak of human metapneumovirus (HMPV) cases at the moment. Although this is a priority for China’s health system, it should not lead to immediate concerns about a new pandemic,” Associate Professor Sanjaya Senanayake, a specialist in Infectious Diseases and Associate Professor of Medicine at The Australian National University, said in a statement. 

“Like many respiratory viruses, it tends to have seasonal peaks of infection (late winter and early spring), although this can vary,” Dr Senanayake explained.

“At this stage, the likelihood is that China is experiencing a bad HMPV season, in the same way that in some years we have an overwhelming flu season. This could be due to a combination of viral and behavioral factors, but it should settle down,” he added.

Although cases of HMPV are high in China, they are expected to peak around this time of year. The apparent rise in cases of HMPV may, in part, be a reflection of better disease surveillance. China has recently vowed to step up its monitoring of emerging respiratory diseases, partially in the wake of COVID-19, and this enhanced vigilance could be uncovering cases that previously went undetected.

Nevertheless, epidemiologists have stressed that China and other countries must maintain transparency about the outbreak to enable the world to respond effectively.

“It is also vital for China to share its data on this outbreak in a timely manner. This includes epidemiologic data about who is getting infected. Also, we will need genomic data confirming that HMPV is the culprit, and that there aren’t any significant mutations of concern,” notes Dr Senanayake.

All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current.