Experts allay fears over pneumonia outbreak in China

Li Lin

Reports of an outbreak of pneumonia cases among children in China have prompted the World Health Organisation (WHO) to ask for more details from the Chinese authorities, which say there is no evidence of novel pathogens being involved.

The cases seem to be clustered around highly-populated urban areas like Beijing and Liaoning, and are mainly being reported in children but also some teachers, according to local media reports. There had been suggestions that some hospitals have been “overwhelmed” by cases, leading to fears that another major epidemic could be on the way.

China has said the outbreak is likely because the lifting of COVID-19 restrictions has caused a surge in other respiratory pathogens, including flu, respiratory syncytial virus (RSV) and SARS-CoV-2, the virus that causes COVID-19, as well as bacterial pathogen Mycoplasma pneumoniae. Last winter, the country still had strong COVID restrictions in place.

WHO asked for more information from China last week on the current burden on healthcare systems as well as trends in the circulation of known pathogens through the International Health Regulations mechanism, and said it had been assured there was “no detection of any unusual or novel pathogens or unusual clinical presentations.”

Prof Paul Hunter, professor in medicine at the University of East Anglia (UEA) in the UK, commented that, for now at least, the evidence does not point to the start of an epidemic due to a novel virus.

“If it was, I would expect to see many more infections in adults,” he said. “The few infections reported in adults suggest existing immunity from a prior exposure.”

Furthermore, the illness mainly seems to cause fever, with no cough or other symptoms, although some patients do show evidence of nodules on the lungs, which indicate infection and inflammation.

“Whilst we can’t make a definitive diagnosis at this stage, the presence of pulmonary nodules tend to suggest a bacterial rather than a viral cause,” said Hunter, who suggested that pneumococcal pneumonia or even influenza could be the cause, as the latter can lead to changes due to secondary bacterial infections.

That view was also voiced by Dr Zania Stamataki, associate professor in viral immunology at the University of Birmingham, who said: “As restrictions lifted and children mixed, it is likely that single respiratory infections or coinfections occur in a background of already circulating harmless viruses, which may cause a more severe disease.”

Researchers have shown that existing harmless circulating viruses can contribute to coinfections that can cause tissue damage, such as unexplained acute hepatitis in children reported by many countries, including the US and UK, in 2022, she added.

WHO is recommending that people in China follow measures to reduce the risk of respiratory illness, which include vaccines against influenza, COVID-19 and other respiratory pathogens as appropriate and maintaining distance from those who are ill.

Photo by Li Lin on Unsplash