What you should know about the human metapneumovirus cases in China

What you should know about the human metapneumovirus cases in China

Getty Images Patients receive infusion therapy at a hospital amid a surge in respiratory illnesses on December 27, 2024 in ShanghaiGetty Images

Beijing has seen a rise in influenza-like HMPV cases, particularly among children, which has been attributed to a seasonal surge

In recent weeks, scenes of hospitals in China crowded with masked people have circulated on social media, sparking fears of another pandemic.

Beijing has since noted a rise in cases of the flu-like human metapneumovirus (HMPV), particularly among children, and has attributed it to a seasonal surge.

But HMPV is not like Covid-19, public health experts say, pointing out that the virus has been around for decades and nearly every child is infected by their fifth birthday.

However, some very young children and people with weakened immune systems may experience more serious illness. Here’s what you need to know.

What is HMPV and how does it spread?

HMPV is a virus that causes a mild upper respiratory tract infection in most people that is virtually indistinguishable from the flu.

The virus, first identified in the Netherlands in 2001, spreads through direct contact between people or when someone touches surfaces contaminated with it.

Symptoms for most people include cough, fever, and nasal congestion.

The very young, including children under two, are most vulnerable to the virus, as are people with weakened immune systems, including the elderly and people with advanced cancer, said Hsu Li Yang, an infectious disease doctor in Singapore.

When infected, a “small but significant proportion” of immunocompromised people develop a more severe disease affecting the lungs, with wheezing, breathlessness and symptoms of croup.

“Many will require hospital treatment, with a smaller proportion at risk of dying from the infection,” said Dr. Hsu.

Why are cases increasing in China?

Like many respiratory infections, HMPV is most active in late winter and spring. Some experts say this is because the viruses survive better in the cold and are transmitted more easily from one person to another as people spend more time indoors.

In northern China, the current HMPV increase coincides with low temperatures that are expected to persist until March.

In fact, many countries in the Northern Hemisphere, including China among others, are experiencing increased prevalence of HMPV, said Jacqueline Stephens, an epidemiologist at Flinders University in Australia.

“While this is concerning, the increased prevalence is likely the normal seasonal increase in winter,” she said.

Data from health authorities in the US and UK show that these countries have also seen an increase in HMPV cases since October last year.

Is HMPV like Covid-19? How worried should we be?

Fears of a Covid-19-like pandemic are overblown, the experts said, pointing out that pandemics are typically caused by novel pathogens, which is not the case with HMPV.

HMPV is present worldwide and has existed for decades. This means that people around the world have “some level of existing immunity due to previous exposure,” Dr. Hsu.

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

“So overall, I don’t think there are any signs of a more serious global problem at this point.”

Nevertheless, Dr. Hsu on general standard precautions such as wearing a mask in crowded places, avoiding crowds when possible when the risk of more severe illness from respiratory virus infections is higher, good hand hygiene and getting vaccinated against flu.

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