During winter in the Northern hemisphere, there is usually an increase in respiratory illnesses like influenza or respiratory syncytial virus (RSV). Another seasonal virus is human metapneumovirus (hMPV), and right now, there are ongoing surges of hMPV in some countries, including China. The World Health Organization has noted that the case numbers of these viruses are within expected ranges for this time of year, there are no unexpected patterns in outbreaks, and there is no cause for alarm.
Health expert Dr. Matthew Binnicker, director of the Clinical Virology Laboratory at Mayo Clinic, agrees that there is no reason for concern. "In the late winter, early spring, [hMPV] can account for five to ten percent of all the respiratory infections that we diagnose in the United States. So it's definitely out there," said Binnicker.
Usually, hMPV causes a mild illness with symptoms that are similar to the common cold. Most people get over these infections without special treatment within a few days. These infections tend to be milder than RSV or the flu, and may cause a runny nose, slight aches, and possibly a cough or sore throat, added Binniker.
Good hand washing practices can help prevent hMPV (and other respiratory viruses); hMPV can spread when people touch a contaminated surface, and coughing can spread the virus onto surfaces. It can also spread through respiratory droplets and close personal contact.
"Human metapneumovirus is transmitted in a similar way to other respiratory viruses, like the flu and COVID and RSV, mainly through respiratory droplets that are produced while an individual coughs or sneezes. It can also be spread through what we call contaminated fomites. So if an infected individual coughs into their hand and then touches a door handle, another person could come along, touch that door handle, and then self-inoculate the virus into their eyes, nose or mouth. And that's a potential way of transmitting the virus as well," said Binnicker.
While most people don't wear face masks anymore, they can also help prevent the spread of respiratory viruses, both when they are worn by people who are infected and can spread an illness, and when they are worn by uninfected people who are then less likely to catch a virus.
It's thought that hMPV originated in an avian host species, though that species is still unknown, and then evolved to infect humans. It was first identified in 2001, although the spillover event may have happened as much as 200 years ago. Those findings have also raised the possibility that the virus went through some intermediate host species. Much is still unknown about the origins of hMPV.
Sources: WHO, CDC, Mayo Clinic, Viruses
