Beijing has acknowledged a surge in cases of HMPV and attributed it to a seasonal spike.

A spokesperson for the World Health Organization (WHO) said data from China indicates that there has been a recent rise in acute respiratory infections but that “the overall scale and intensity of respiratory infectious diseases in China this year are lower than last year”.

Many countries in the northern hemisphere are experiencing an increased prevalence of HMPV, said Associate Professor Jacqueline Stephens, an epidemiologist at Flinders University in Australia.

The UK Health Security Agency said that HMPV is at a “medium” level of activity, and the rate of positive cases had only “increased slightly” compared with the start of 2024, when it was 4.18%.

What is HMPV?

According to the Cleveland Clinic, human metapneumovirus (HMPV) is a virus that brings on flu-like symptoms, with a heightened risk of developing into more serious illnesses, such as bronchitis or pneumonia, in those most vulnerable, e.g. the elderly, young children and immunocompromised individuals.

The illness causes a mild upper respiratory tract infection, which commonly mimics symptoms of flu, including cough, fever and nasal congestion. Other symptoms can include a sore throat, wheezing, shortness of breath and a rash.

The virus is caught through direct contact with others or surfaces contaminated with the virus.

The very young, including children under two, are most vulnerable to the virus, along with those with weakened immune systems. It was first identified in the Netherlands in 2001, so, unlike with Covid-19, many people across the world already have some degree of existing immunity due to previous exposure.

Experts pointed out that pandemics are typically caused by novel pathogens, which is not the case with HMPV.

“Almost every child will have at least one infection with HMPV by their fifth birthday and we can expect to go on to have multiple reinfections throughout life,” Paul Hunter, a medical professor at the University of East Anglia in England, told the BBC.

Why are cases on the rise?

In northern China, the current HMPV spike comes at a time of low temperatures that are expected to continue through to March. Viruses thrive in cold weather as they are able to transmit between people more easily.

On 18 December the European Centre for Disease Prevention and Control released a report that said trends from the last two years suggest a return to a more regular timing of seasonal respiratory virus epidemics following the Covid-19 pandemic.

As HMPV is globally present and has been around for decades, experts have suggested there aren’t currently any signs of a more serious global issue.

International SOS recently released its annual interactive Risk Map for 2025.