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expert reaction to ProMED report on undiagnosed pneumonia in children in China

Scientists react to news of undiagnosed pneumonia in children in China. 


Prof Paul Hunter, Professor in Medicine, University of East Anglia (UEA), said:

“At present there is too little information to make a definitive diagnosis of what is causing this epidemic in China.

“From the original post The outbreak is predominantly being reported from Beijing, Liaoning and other places so over some considerable distance. The epidemic is predominantly in children but illnesses are being reported in teachers at least in Liaoning.

“The illness in children is fever with no cough or other symptoms, but in some cases, pulmonary nodules can be seen on Chest X-Ray. At present, we don’t know the age group mostly affected but it seems school-age children are certainly affected.

“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. Pulmonary nodules in children are seen in pneumococcal pneumonia and cough may be absent.  Influenza can catch patchy changes on chest X-ray, often due to secondary bacterial infections so could also be in the frame. Others have suggested Mycoplasma infections which caused outbreaks of infection during autumn even prior to covid and tend to preferentially affect children and younger adults. However, the symptoms and Chest X-Ray appearance are not entirely consistent with Mycoplasma.

“There may also be more than one infectious cause of the current epidemic.

“Overall, this does not sound to me like an epidemic due to a novel virus. If it was, I would expect to see many more infections in adults. The few infections reported in adults suggest existing immunity from a prior exposure.

“If this epidemic is due to a known infection then why is it apparently so bad this year? Last year China was still pursuing zero COVID strategies and so this is the first full winter without restrictions. One explanation for the current issue is that because of restrictions the population immunity to whatever is causing the current illnesses as we saw last year in the UK with Influenza and Rotaviruses.

“So at present, there is insufficient information on which to make a definitive assessment of the wider risk from this reported epidemic. My feeling is that it won’t lead to a public health emergency of international concern, but I would not totally rule out that possibility until we have a definitive diagnosis.”


Dr Zania Stamataki, Associate Professor in Viral Immunology, University of Birmingham, said:

“There is currently no evidence that the increase in paediatric pneumonia cases in China may be due to a new virus. 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. Recent work from several groups published earlier this year (see commentary here) showed that existing harmless circulating viruses can contribute to coinfections that can cause tissue damage, such as the unexplained acute hepatitis in children reported by many countries in 2022. It will be very interesting to see the data from the infections detected in the children with pneumonia in China.”


Prof David Heymann, Professor of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, said:

“It is important to consider that there is likely a background of seasonal respiratory infections – the challenge is to discern the outbreaks and determine the cause. There are many different known viruses that could be the cause and these must all be sought in testing. At the same time isolation and sequencing will also provide answers.”


Prof Francois Balloux, Professor of Computational Systems Biology and Director, UCL Genetics Institute, UCL, said:

“The current wave in China is likely caused by different respiratory pathogens such as RSV or the flu. Though it is also probable that substantial proportion of cases may be due to the bacterium Mycoplasma pneumoniae, which is generally fairly harmless.”

“China is likely experiencing a major wave of childhood respiratory infections now as this is the first winter after their lengthy lockdown, which must have drastically reduced the circulation of respiratory bugs, and hence decreased immunity to endemic bugs. This phenomenon of ‘lockdown exit’ waves of respiratory infections is sometimes referred to as ‘immunity debt’.”

“Other countries, including the UK, experienced big waves of respiratory infections and hospitalisations in kids during their first winter after pandemic restrictions had been lifted.”

“Since China experienced a far longer and harsher lockdown than essentially any other country on earth, it was anticipated that those ‘lockdown exit’ waves could be substantial in China.”

“Unless new evidence emerged, there is no reason to suspect the emergence of a novel pathogen.”




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For all other experts, no reply to our request for DOIs was received.

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