Exact symptoms to look out for as ‘mystery virus’ cases soar

The virus can be very similar to the flu

First identified in the Netherlands in 2001, HMPV is a flu-like respiratory disease that will lead to a mild upper respiratory tract infection.

It spreads through direct contact between people or when someone touches surfaces contaminated with it, the BBC reports.

In recent weeks, pictures have spread online of crowds of masked people in hospitals in China, and Beijing has acknowledged a surge in case of the flu-like illness, particularly among children.

But this is not a new virus, with experts making clear that HMPV has existed for decades.

In the majority of cases, HMPV causes only mild illness, but in some very young children, the elderly and people with weakened immune systems, it can be more serious. In the most serious cases, it can lead to severe complications affecting the lungs, such as pneumonia.

The BBC reports that HMPV can be "practically indistinguishable" from the flu.

The key HMPV symptoms to watch out for

According to Public Health Scotland, the most common symptoms are:

• common cold or flu-like symptoms (cough, runny nose or nasal congestion, fever and/or chills)
• asthma flare-ups
• sore throat
• wheezing
• dyspnoea (shortness of breath)

Symptoms of severe infection with HMPV include:

• acute bronchitis (inflammation of the airways of the lungs, sometimes called a ‘chest cold’)
• bronchiolitis (inflammation and congestion in the small airways of the lungs in young children and infants)
• pneumonia (infection of the lungs)

Symptoms will usually take three to six days to clear after infection.

Why are cases rising in China, and are they rising elsewhere?

An increase in HMPV cases during the winter months is common, just like with other respiratory infections. These viruses are helped by people spending more time indoors, and the fact they survive better in the cold.

Low temperatures in northern China, expected to last until March, have helped the virus, the BBC reports.

Surges in cases have also been reported in India, Kazakhstan and Malaysia, with the UK also experiencing a slight increase in cases.

The latest data from the UK Health Security Agency (UKHSA) shows cases of HMPV rose by 4.15 percentage points between October and December 2024. This rise means the virus is at a “medium” level of activity, according to the UKHSA.

Speaking to the BBC, Jacqueline Stephens, an epidemiologist at Flinders University in Australia, said the increased prevalence of HMPV is “likely the normal seasonal increase seen in winter.”

In Ireland, the Health Protection Surveillance Centre (HPSC) does not report cases of HMPV, as its focus is on other viruses instead.

A HSE spokesperson told the Irish Sun they would “closely monitor” the situation, but as it is “not a notifiable disease” and so “routine surveillance data on this virus are not available.”

Should we be worried about HMPV?

There is no major cause for concern about HMPV, and we’re highly unlikely to see a situation anything like the Covid pandemic. The main reason for this is that, because HMPV has existed globally for decades, there is far more resistance and immunity in the global population than there was for Covid-19.

HMPV also has milder symptoms than Covid-19. All of this means that if there was a serious spread from China, other nations would be much better prepared to deal with rising cases than they were with Covid.

Professor Paul Hunter from the University of East Anglia said: “Almost every child will have at least one infection with HMPV by their fifth birthday and we can expect to go on to to have multiple reinfections throughout life.

“It is one of the leading viral causes of respiratory infections in children under five-year-olds.”

What can I do to protect myself against HMPV?

There is no vaccine against the virus, but getting a flu vaccine can reduce your risk of serious complications from HMPV.

Because it is a virus, antibiotics will not have an effect on HMPV, and the main treatment is to manage symptoms.

If you are at higher risk of complications from catching the virus, then the usual advice applies: wash your hands, wear a mask in public and avoid crowds if possible.

If you’re in a higher risk category and are concerned about HMPV, or are experiencing severe or persistent symptoms, you can visit your GP for a test and diagnosis.