Cases of the respiratory virus known as HMPV – which has symptoms similar to those of the common cold, flu, and Covid-19 – have been surging in China, prompting fears that another global pandemic is on the way.
Outbreaks of the human metapneumovirus have hit numerous regions of the country and, given that there’s no vaccine, people in China are being urged to wear masks, while authorities are closely monitoring the rising case numbers.
But what is the virus and what are its symptoms? Here’s what you need to know.
What is Human metapneumovirus?
Human metapneumovirus (HMPV) is a commonly found virus that can cause respiratory illness. Although the virus typically has no symptoms in healthy adults, it can cause serious sickness in older adults, those with asthma, babies, and children according to the National Institute of Allergy and Infectious Diseases (NIAID).
Humans, however, continue to become infected throughout their lifetimes since the illness only produces a minimal or ineffective immune response
Companies are developing vaccinations to protect against it. According to NAID, Moderna, the manufacturer of the Covid-19 vaccine, has just ended an early trial of an mRNA vaccine against HMPV and parainfluenza.
According to respiratory virus surveillance systems run by the US Centers for Disease Control and Prevention, cases of HMPV increased this spring in America.
In the States, the most vulnerable populations for these infections – young children and the elderly – were dominant in hospital intensive-care units. Nearly 11 per cent of those tested were HMPV positive at its peak in mid-March, a figure that is roughly 36 per cent higher than the typical, pre-pandemic seasonal peak of seven per cent test positivity.
What are the symptoms?
According to the American Lung Association, the majority of HMPV patients experience moderate upper respiratory symptoms resembling a cold. These may consist of a cough, congestion in the nose or runny nose, a sore throat, aches, and fever.
A brief illness brought on by the virus typically lasts two to five days and resolves on its own. Patients may choose to treat their condition using over-the-counter medications, like a decongestant.
However, in extreme circumstances, the virus might cause asthma attacks, wheezing, and breathing problems. Anyone experiencing these symptoms is encouraged to visit their doctor because they might require a stronger medication or a temporary inhaler.
HMPV is transmitted by intimate contact with an infected person or by touching contaminated objects or surfaces, just like other respiratory viruses.
Some patients have seen the virus lead to bronchiolitis and pneumonia.
Have there been HMPV cases in the UK?
There have – though not quite on the scale of the breakouts in China.
HMPV is one of the illnesses monitored through the government’s weekly flu and Covid-19 reports.
A report covering samples sent to laboratories in England found that, in the final week of 2024 – between December 23 and 29 – 4.5 per cent of people had tested positive for HMPV, a slight increase on the previous week.
To put this figure into context, 29.5 per cent of lab-tested swabs were positive for influenza, while 2.5 per cent were positive for Covid-19.
Could there be a lockdown in China?
China has upped its monitoring of HMPV but there’s no signs the country will go into a Covid-style lockdown just yet.
Its foreign ministry spokesperson Mao Ning said last week: “Respiratory infections tend to peak during the winter season.
“The diseases appear to be less severe and spread with a smaller scale compared to the previous year.”
For now, the country is continuing to log all cases.
How was Human metapneumovirus discovered?
The virus was identified by scientists in the Netherlands in 2001.
Scientists took 28 samples from children in the Netherlands who had respiratory infections that were not explained. Even though several became critically unwell and needed mechanical ventilation, no known infections were found in their blood.
The samples were cultivated in diverse cell types from dogs, chickens, and monkeys before being examined under an electron microscope. They observed something that appeared to share structural similarities with the paramyxoviridae family of viruses, which are known to cause respiratory illnesses like measles, mumps, and respiratory syncytial virus, or RSV.
A detailed examination of the virus’s genome revealed a close relative in the form of the bird-infecting avian metapneumovirus. The novel pathogen was given the name human metapneumovirus. It probably evolved from birds to humans at some point, according to scientists.