The spike in respiratory illnesses in China raised fears of another novel virus. However, the officials say the infections are caused by well-known pathogens.
In mid-November, the disease reporting service ProMED notified about the "undiagnosed pneumonia" cases in northern China provinces.
According to the report, pediatric hospitals in Beijing, Liaoning, and other places were “overwhelmed with sick children,” whereas schools and classes were on the verge of suspension. This made parents question whether the authorities were covering up the epidemic.
Mr. [W], a Beijing citizen, told ProMED: "Many, many are hospitalized. They don't cough and have no symptoms. They just have a high temperature (fever) and many develop pulmonary nodules."
In response to these reports, the WHO requested the Chinese officials to provide additional epidemiologic and clinical information, as well as laboratory results from these reported cases.
What caused the surge?
Chinese officials say the increase in respiratory illnesses is due to the lifting of COVID-19 restrictions, as the country ended its zero-COVID policy in January 2023.
The circulation of other known pathogens, such as influenza, adenovirus, respiratory syncytial virus (RSV), and Mycoplasma pneumoniae, also drove the spike. Both RSV and M. pneumoniae are known to affect children more than adults.
In the report published last week, the WHO said some of these increases are occurring earlier in the season than in previous years but are "not unexpected" given the removal of COVID-19 restrictions, as experienced in other countries.
The Chinese officials say that since mid-October, they have enhanced surveillance for respiratory illnesses, including, for the first time, caused by M. pneumoniae. The bacteria usually cause mild respiratory system infections but sometimes may lead to a more severe disease that requires hospitalization.
The disease spreads through respiratory droplets and often between people who live together since they spend a lot of time together. The outbreaks of M. pneumoniae infections occur mostly in crowded settings, such as schools or hospitals.
The infection can be treated with antibiotics, but most people recover from the disease without taking them.
An increase in M. pneumoniae cases is also reported in France, where “lung infections in children under the age of 15 reached levels unseen in the last ten years,” according to le Parisien.
Is there a novel virus in China?
Chinese authorities told the WHO that there has been no detection of "any unusual or novel pathogens or unusual clinical presentations," and the current surge is only a general increase in respiratory illnesses.
Paul Hunter, a Professor of Medicine at the University of East Anglia, says that the spike in respiratory illnesses does not sound “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.
Prof. Paul Hunter
The SARS-CoV-2 virus that caused the global COVID-19 pandemic emerged in the Chinese city of Wuhan in late 2019. Since then, Chinese officials have been criticized for withholding data about the possible origins of the virus and underreporting the severity of the outbreak in the country.
Scientists still don't have a definitive answer explaining the origins of SARS-CoV-2, but the evidence suggests that the virus jumped from animals to humans in the Huanan Wildlife Market in Wuhan.
Should I avoid traveling to China?
The WHO does not recommend any specific measures for travelers to China but says people should avoid travel experiencing symptoms of respiratory illness.
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