The World Health Organization (WHO) noted an upsurge of unidentified pneumonia-like respiratory illnesses among children in Northern China, and asked China for more information. This is significant as previous outbreaks of severe respiratory illnesses have started out in this fashion, but such WHO requests for more information on disease clusters are routine as part of its monitoring. No “unusual or novel pathogens” have been found, according to China, which attributed it to an increase in multiple pathogens and the lifting of COVID restrictions.
Earlier this month, China’s National Health Commission reported a nationwide increase in respiratory disease incidence, mostly among children. This increase was attributed to lifting of COVID restrictions and the arrival of the cold season, and due to circulating known pathogens including Mycoplasma pneumonia and RSV, which are known to affect children more than adults.
On 22 November 2023, the WHO identified media and ProMED reports about clusters of undiagnosed pneumonia in children’s hospitals in Beijing, Liaoning and other places in China. The WHO requested from China additional epidemiologic and clinical information, as well as lab results from these cases and data about recent trends in circulating respiratory pathogens.
The WHO held a teleconference with Chinese health authorities and received data indicating an increase in outpatient consultations and hospital admissions of children due to Mycoplasma pneumoniae pneumonia since May, and RSV, adenovirus and influenza virus since October. Some of these increases are earlier in the season than usual, but not unexpected given the lifting of COVID restrictions, as similarly experienced in other countries. No changes in the disease presentation were reported by the Chinese health authorities, who said no unusual or novel pathogens or unusual clinical presentations had been detected, but only the general increase in respiratory illnesses by known pathogens. Local hospitals had not been overloaded by new cases.
In the current outbreak of respiratory illness, the reported symptoms are common to several respiratory diseases and, as of now, at the present time, Chinese surveillance and hospital systems report that the clinical manifestations are caused by known pathogens in circulation. M. pneumoniae is a common respiratory pathogen and a common cause of paediatric pneumonia, and is readily treated with antibiotics.
China has stepped up its influenza-like illness (ILI) and severe acute respiratory infections (SARI) sentinel surveillance system since mid-October, including for M. pneumoniae.
There is limited detailed information available to fully characterize the overall risk of these reported cases of respiratory illness in children. However, due to the arrival of the winter season, the increasing trend in respiratory illnesses is expected; co-circulation of respiratory viruses may increase burden on health care facilities.
According to surveillance data reported to WHO’s FluNet and published by the National Influenza Centre in China, ILI was above usual levels for this time of year and increasing in the northern provinces. Influenza detections were predominantly A(H3N2) and B/Victoria lineage viruses.
The WHO advice was for people in China to take measures against respiratory illnesses, including vaccines, masking and social distancing. It also does not recommend any specific measures for travellers to China.