SINGAPORE: China is seeing a surge in respiratory infections, including cases of the flu-like human metapneumovirus (HMPV) amid an annual winter spike across northern provinces, particularly among children aged 14 and below. 

Without releasing figures, China’s Center for Disease Control and Prevention (CDC) on Jan 2 reported an upward trend in overall respiratory diseases recorded between Dec 23 to Dec 29.  

It follows an increase in caseloads recorded in the week of Dec 16 to Dec 22, Chinese CDC officials said, announcing that they are piloting a monitoring system for “pneumonia of unknown origin” which includes establishing protocols for laboratories and disease control agencies to verify and handle cases. 

Photos and videos have also circulated widely on Chinese social media sites, showing huge crowds and snaking queues forming at hospitals, clinics and medical centres. 

China is still in “the season of high incidence of respiratory diseases”, the Chinese CDC said, reminding members of the public to take protective measures such as wearing masks, being up to date with vaccinations and maintaining proper hygiene practices. 

“Respiratory infections tend to peak during the winter season in the northern hemisphere,” Chinese foreign ministry spokesperson Mao Ning told a press conference in Beijing on Jan 3, responding to questions about the spread of respiratory diseases and potential travel restrictions. 

“The diseases appear to be less severe and spread with a smaller scale compared to the previous year,” she said. 

What is HMPV? 

HMPV, or human metapneumovirus, is a respiratory illness with symptoms similar to the common flu. 

These include coughing, fever, nasal congestion and shortness of breath.

In severe cases, the virus can lead to complications like pneumonia or bronchitis. 

“It can cause upper and lower respiratory disease in people of all ages, especially among young children, older adults and people with weakened immune systems,” the US Centers for Disease Control and Prevention (US CDC) said in a health advisory, adding that the estimated incubation period could last anytime between 3 to 6 days. 

The virus is “most active” during late winter and spring in temperate climates. Young children, the elderly and those with weakened immune systems are most vulnerable, it added.  

Like other respiratory diseases like COVID-19 and the flu, the HMPV virus spreads through: 

• Close contact with an infected person, such as touching or shaking hands
• Droplets from sneezing and coughing
• Touching objects or surfaces that have the virus on them. 

Why are cases rising? 

Infectious disease experts told CNA that China's rise in cases is "consistent with global patterns", where numbers rise typically during late winter months.

The current spike coincides with China’s cold weather and low temperatures are projected to last until March. 

Dr Khoo Yoong Khean from the Duke-NUS Centre for Outbreak Preparedness, said HMPV infections or outbreaks are not uncommon especially among children below the age of five. 

“Infectious disease surveillance has strengthened quite a bit since COVID-19, so it’s possible we are picking up cases more easily due to better surveillance,” Dr Khoo said, adding that it is “worthwhile” to monitor these outbreaks so that “(we) can act accordingly if we notice any sudden rise in cases, or shift in transmission patterns”.

Professor Paul Tambyah, a Senior Consultant at the National University Hospital (NUH)’s Division of Infectious Diseases, noted that Chinese health officials have greatly stepped up surveillance of acute respiratory infections with better diagnostics and deployment of technology. 

“It is not surprising that more HMPV infections are being picked up. This does happen in China every winter on a regular basis, especially in northern China,” Prof Tambyah said. 

“The bottom line is that we should not be overly concerned as there are no reports of a major public health impact from the increased detection in Northern China (but) of course, all this could change with more data,” he added. 

How does it compare to COVID-19? 

In contrast to COVID-19, HMPV is widespread in young children, said Prof Tambyah.

But he adds that the danger lies in the virus aggravating pre-existing health conditions like asthma, which can lead to moderate respiratory illness and sometimes require hospitalisation. 

“Mortality is rare with HMPV,” said Prof Tambyah, adding that HMPV-related deaths usually occur when the virus is detected with other more virulent viruses such as influenza. 

But unlike COVID-19, where vaccines and antiviral treatment such as Paxlovid have been made available, there is no specific antiviral therapy to treat HMPV and currently no vaccine to prevent the disease despite the virus being discovered decades ago.  

Cambodian health officials have urged people to take extra precautions, especially when travelling.

“Because the weather is not very cold (in Cambodia), HMPV is not as severe as the flu and most children have recovered,” the health ministry said.

While most cases are mild, “about 6 to 16 per cent of infected children could progress” to more severe conditions like bronchitis or pneumonia, officials said.

In Singapore, “HMPV has long been recognised,” said Prof Tambyah. “In fact, it was reported as the second most common respiratory viral infection in children, after the respiratory syncytial virus (RSV), almost 20 years ago.”  

CNA has reached out to Singapore’s Ministry of Health to find out more about the current HMPV situation. 

How can we protect ourselves? 

The uptick in HMPV cases comes five years after the world was first alerted to the emergence of the coronavirus in Wuhan, China, which went on to become a global pandemic - overwhelming hospitals, and sending countries into lockdown. 

In Singapore, lessons learned from COVID-19, from better surveillance systems to good hygiene practices like washing hands thoroughly and masking up especially in crowded spaces, will serve us well, said Dr Khoo from Duke-NUS.

Since most HMPV infections occur in younger children, Prof Tambyah advised families travelling with children to be mindful.

“If Singaporeans are travelling with children, they will need to pay attention to respiratory infections that appear more prolonged or more severe than usual and seek medical attention promptly.” 

“Our surveillance system also is well set up to pick up cases locally if there are and we are up to date with global surveillance data of infectious diseases,” said Dr Khoo.   

“If there is any hint of a more serious or widespread respiratory viral infection almost anywhere in the world, I think that we would be able to react quickly and efficiently,” said Prof Tambyah.

"Fortunately, that does not seem to be the case with HMPV."