People in the UK have been advised to avoid some medical settings and to wear masks in some hospitals and clinics after a rise in cases of a virus now as HMPV. Infections caused concern when there were reports of hospitals in China being overwhelmed with cases of illness and no clear reason why.
The infections have been identified as HMPV – Human metapneumovirus – and cases are on the rise in the UK.In the latest figures released by the UK Health Security Agency it found that HMPV positivity increased to 4.5%, with the highest positivity in those aged under 5 years at 10.0%.
An expert has explained the virus has been around for hundreds of years and the symptoms are indistinguishable from a common cold or flu – meaning millions of people have been catching it for years without knowing what it was.
Paul Hunter, Professor of Medicine, University of East Anglia, told The Conversation : “It is not a new infection and has probably been circulating in humans for centuries. The virus was first linked to human illness about 25 years ago by Dutch researchers who identified the virus in children who had a similar illness to RSV.
“This same study showed that the virus was not new as archived samples from the 1950s showed that all children in the study had antibodies to HMPV by their fifth birthday. Other research has suggested that HMPV diverged from avian MPV about 300 years ago.Like all viruses, HMPV evolves over time. But its rate of evolution is relatively slow compared with some other viruses.
“HMPV is one of the commoner respiratory viruses. Even after childhood, we can expect multiple repeat infections throughout life. The disease is found around the world, with most infections occurring during the winter months. The virus causes an illness that is very difficult to distinguish from many other respiratory infections without testing.
“Most infections are a mild cold-like illness, and people recover within about two to five days. However, in young children, the illness can be more severe and similar to the chest infection caused by RSV. HMPV in children generally doesn’t cause as severe an illness as RSV and is less likely to require admission to an intensive care unit.
“In older adults (over 65), and those with certain existing health conditions, HMPV can cause more severe disease. This is particularly the case in people who have heart and lung disease, including asthma. There is no specific treatment for HMPV. Instead, patients are made comfortable until they recover on their own. If people become very ill then treatment consists of supporting normal breathing.
“There is no vaccine against HMPV. However, several vaccines are in the process of being developed. A combined HMPV and RSV mRNA vaccine has recently started trials.”
In the UK, HMPV-positive samples increased substantially in the weeks before Christmas rising to 4.5% of samples tested in the last week.
The HMPV results for the same week last year and the year before that are about the same. So in the UK at least, levels of HMPV infections seem to be about what we would expect for this time of the year.
Professor Hunter said: ” In China, influenza remains the most commonly detected respiratory virus, just like in the west. In its latest report, the World Health Organization has suggested that, currently, the increase in respiratory pathogens in China is “within the range expected for this time of year”. If health services are being overwhelmed in China, flu is much more likely to be the main concern.
“So, I think we can be pretty confident that we are not going to see a substantial additional global risk to public health from HMPV.
“The situation with HMPV is very different from the situation with COVID in early 2020. Unlike COVID, HMPV is not a new infection and there is already substantial immunity in most people from many previous infections.”