Chinese hospitals have been “overwhelmed with sick children” as an outbreak of pneumonia escalates in cities across the country, including Beijing, according to reports.

ProMed – a large, publicly available surveillance system which monitors human and animal disease outbreaks worldwide – issued a notification late on Tuesday detailing a reported epidemic of “undiagnosed pneumonia” in children. 

It was a ProMed alert in late December 2019 that brought a mystery virus later named Sars-Cov-2 to the attention of many doctors and scientists, including senior officials at the World Health Organization.

The latest post, based on a report from the Taiwanese outlet FTV News, said that hospitals in the capital Beijing and Liaoning – almost 500 miles northeast – were struggling amid an influx of children sick with pneumonia. 

“Many, many are hospitalised,” Mr Wei, a Beijing citizen, told FTV News. “They don’t cough and have no symptoms. They just have a high temperature (fever) and many develop pulmonary nodules.”

In an editor’s note, ProMed said: “This report suggests a widespread outbreak of an undiagnosed respiratory illness ... It is not at all clear when this outbreak started as it would be unusual for so many children to be affected so quickly. The report does not say that any adults were affected suggesting some exposure at the schools.”

The alert added that more definitive information is needed to determine the cause and scope.

However, the outbreak could be linked to Mycoplasma pneumoniae, also known as “walking pneumonia”, which is reportedly surging as China enters its first winter without its stringent Covid-19 lockdown in place. 

Other countries, including the UK and US, saw similar surges in diseases such as RSV and flu once pandemic restrictions were lifted, as years of suppressed circulation hit immunity among the population. 

Symptoms of walking pneumonia – which generally affects young children – include a sore throat, fatigue, and a lingering cough that can last for weeks or months. In severe cases, this can eventually deteriorate into pneumonia. 

Last month, local media reported that hospitals nationwide were seeing an increase in infections, with clusters of cases often emerging in schools and nurseries. 

“It is the first wave of mycoplasma pneumoniae infections since most Covid-19 containment measures were lifted at the beginning of this year,” Zhou Huixia, director of the children’s medical centre at the Seventh Medical Center of the Chinese PLA General Hospital, told China Daily.

“The wave has appeared particularly ferocious since the National Day holiday in early October,” she said. “Compared to previous years, we found more patients with mixed infections, drug resistance and lobar pneumonia.”

She added that the “intense” wave of infections is expected to peak in November, and may coincide with an uptick in other infectious respiratory diseases that were suppressed during lockdowns. 

Last month, Li Yuchuan, director of the outpatient department of Beijing Children’s Hospital, also told China Voice that the hospital has been struggling with paediatric respiratory diseases this year.

“It has been running at a relatively high level. The first peak occurred from mid-to-late February to late March, when influenza was the main cause; the second peak occurred in May, when there were a variety of pathogens, such as RSV; the third peak appeared in September,” said Dr Li, adding that the facility has had to boost capacity to cope. 

The recent surge in Mycoplasma pneumoniae has also raised concerns about growing antibiotic resistance, as the bacteria is increasingly sidestepping macrolides – a preferred class of drug – and China has the world’s highest rates of resistance. 

A study from February 2022 found that macrolide resistance was identified in more than 80 per cent of mycoplasma pneumoniae found in children hospitalised with the bacteria in China. 

Yet Chinese experts stressed that very few children have died from “walking pneumonia” to date. 

“There is a steady number of patients developing severe cases, but there are very few critical cases, and there are no related deaths so far,” Hua Shaodong, a paediatrician at the Beijing Children’s Hospital, told China Daily. “The average days in hospital for hospitalised patients is around seven to 14 days.”