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The scenes are eerily familiar: crowded hospitals in China overrun by masked patients seeking medical help as the infection tears through the population.
But this time it is not Covid-19 that does the damage. Instead, doctors are struggling to deal with high rates of illness caused by a different organism known as human metapneumovirus or HMPV.
The virus causes cold and flu-like symptoms, but can be dangerous for certain groups, particularly children and the elderly.
And, worryingly, other countries are also reporting a rise in cases, which have doubled in the UK in just a month.
So how worried should you be? Could this be the start of the next pandemic? Here you will find everything you need to know…
What is HMPV?
HMPV belongs to the same family of infectious bacteria as respiratory syncytial virus (RSV), which is already a common source of the winter lung infection bronchiolitis, hospitalizing around 30,000 children and 18,000 adults in the UK each year.
Respiratory viruses increase in winter because we spend more time indoors and closer to each other, allowing insects to spread more easily.
HMPV was first officially identified by a team of Dutch scientists in 2001, but some evidence suggests it has been circulating for hundreds of years.
Doctors are struggling to deal with high rates of illness caused by a different organism known as human metapneumovirus or HMPV. Pictured is the waiting room of a hospital in Hangzhou, China.
Experts have warned that HMPV, which produces flu-like symptoms, can remain in the body for days and can therefore easily be transmitted to other people.
You may not have heard of it because it is just one of many viruses (at least 200 at last count) known to cause cold and flu symptoms in the UK each year.
In fact, it is estimated that almost every child in the country has had at least one HMPV infection by the time they turn five, which, in most cases, would have presented as a cold.
Why do we only find out about it now?
HMPV has hit the headlines due to a rise in cases in China, especially in children, with social media flooded with images of hospitals being overrun.
While it has not released official data, China says there has been an increase in HMPV cases in the north of the country, while India, Malaysia and Kazakhstan have also announced an increase.
How dangerous is it?
For most healthy adults, it is unlikely to cause serious problems. But in very young babies, as well as the elderly or anyone with a chronic illness such as leukemia or rheumatoid arthritis, HMPV can cause worrying complications.
These include pneumonia and bronchiolitis (especially in babies), where the virus causes dangerous inflammation in the small airways. Bronchiolitis kills between 20 and 30 babies a year in the UK. And, especially in the elderly, acute respiratory infections increase the risks of heart attacks and strokes.
A 2018 study by University College London suggested that viral infections could account for almost one in 30 heart-related deaths in people over 75.
How would I know if I have it?
You wouldn’t do it unless you were very sick and they gave you a test. But in the vast majority of cases, the main symptoms are very similar to those of a common cold: cough, congestion or runny nose, sore throat and mild fever.
As with other viruses, these are caused by the body’s immune system trying to fight them. Some people may also experience nausea and vomiting, but in most cases they are very short-lived: symptoms usually disappear within two to five days.
He probably wouldn’t be tested for the infection unless it caused complications that meant he ended up in hospital, where doctors might need to clarify what was causing his symptoms.
If so, they could perform a rapid antigen test, like the home Covid tests used during the pandemic, where a nasal swab is examined for the presence of the hMPV virus.
Or they can use a more sensitive, high-tech PCR test (again, similar to those deployed for Covid) that looks for traces of the virus’s genetic material in nasal swabs.
Are the cases in China the start of a pandemic?
Experts have noted that while HMPV is usually detected in the winter period, severe infection rates may be higher in China than would normally be expected.
But according to leading British experts, this outbreak is unlikely to be the start of a pandemic.
HMPV replicates slowly and mutates into new strains at a much slower rate than the flu or Covid. Even if this HMPV outbreak is due to a new strain of the virus (for which there is no evidence yet), the expert consensus is that it is likely to be similar enough to other circulating strains and that our body’s defenses will already have some degree of immunity.
A child wearing a face shield is held by an adult while waiting to be seen by medical staff at a hospital in Hangzhou, China.
In the same way as other cold, flu or Covid viruses: HMPV is largely airborne and spread from person to person through inhalation of contaminated droplets.
“Although HMPV mutates over time and new strains emerge, it is not a virus that we consider to have pandemic potential,” says Dr. Andrew Catchpole, scientific director of HVIVO, an independent research body based in the United Kingdom that helps to develop vaccines. against infectious diseases.
Compare this virus to Covid-19: it was a completely new pathogen. The human immune system was not well equipped to deal with it until vaccines arrived.
Pandemics usually occur in two ways. Either a completely new pathogen enters the human population, or a new variant of an existing virus, made up of a combination of a human and animal version, forms a powerful new organism. Could this have happened? Dr Catchpole adds: “There is no animal reservoir for HMPV-related viruses.”
Is he going to invade the NHS?
According to the UK Health Security Agency, HMPV is currently at what it describes as a “medium” level of activity.
For example, in the week ending December 23, 2024, 4.53 percent of hospitalized patients in England who underwent a PCR test for the virus tested positive, up from 2.5 percent earlier. of the month and five times the amount that tested positive in the summer.
That said, the numbers are not radically different from the same period last year. To put it in context, the number of people who tested positive for flu during the same week was more than 14 percent and for RSV was 7.35 percent.
Paul Hunter, a professor of medicine and infectious diseases expert at the University of East Anglia, said it is possible that better testing methods are detecting more cases, rather than infections rising dramatically.
How is it spread?
In the same way as other cold, flu or Covid viruses: it is largely transmitted through the air and passes from one person to another through inhalation of contaminated droplets.
These travel deep to the lungs, where the virus hijacks healthy cells to use as a reproduction “factory” and spread further.
However, like cold and flu viruses, HMPV can also be contracted by touching contaminated surfaces or direct contact with an infected person, especially if they touch you in areas where the virus can easily invade the body. such as around the mouth, nose or eyes. Symptoms appear within three to six days.
The above are clips from videos claiming to show overwhelmed hospitals in China.
How can I avoid getting infected?
The most effective defense is the same basic hygiene measures for any winter virus: washing your hands with soap and warm water (to remove viral particles hiding on the skin) and periodically cleaning surfaces in the home.
Some experts recommend staying away from high-touch surfaces, such as handrails and doorknobs in crowded places, and wearing masks in crowded environments.
How do I treat it?
Most cases do not need treatment other than common over-the-counter remedies for cold and flu symptoms, such as acetaminophen and ibuprofen.
Is there a vaccine?
No, but there are several in development aimed at babies.