Chinese health authorities have provided the requested data on an increase in respiratory illnesses and reported clusters of pneumonia in children, and have not detected any unusual or novel pathogens, the World Health Organization (WHO) said on Thursday.
The WHO had asked China for more information on Wednesday after groups including the Program for Monitoring Emerging Diseases reported clusters of undiagnosed pneumonia in children in north China.
As per the rule, China responded to the WHO within 24 hours. The WHO had sought epidemiologic and clinical information as well as laboratory results through the International Health Regulations mechanism.
Epidemiologists have warned that as, China heads into its first winter since the lifting of zero-Covid restrictions, natural levels of immunity to respiratory viruses may be lower than normal, leading to an increase in infections.
Several countries, including the US and the UK, experienced large waves of respiratory viral infections in the first winter after Covid restrictions were lifted as people had lower natural levels of immunity. For young children, lockdowns delayed the age at which they were first exposed to common bugs.
On 13 November, China’s National Health Commission held a press conference about the increase in respiratory disease cases. The health authority said that these cases were linked to pathogens such as influenza and mycoplasma pneumoniae, a common bacterial infection that typically affects younger children.
The WHO said earlier on Wednesday that it had asked China for more information about clusters of pneumonia in children in northern China, stressing that such requests were “routine”.
Earlier this month, one of China’s leading hospitals reported a surge in mycoplasma pneumoniae and other respiratory diseases among children in September and October. Beijing Friendship hospital said the average number of daily outpatient and emergency visits to the paediatric department had increased to more than 1,600, due to the “rapid spread” of respiratory infections.
But in recent weeks the number of infected children in several provinces appears to have fallen, according to Sixth Tone, a local media outlet.
On Monday, Wang Quanyi, the deputy director of China’s Centre for Disease Control and Prevention, said that mycoplasma pneumonia was no longer among the top three respiratory infections among children in Beijing.
Wang said: “Due to the co-circulation of multiple pathogens, the overall number of infections will show an upward trend … medical institutions must be prepared to deal with the pressure”.
The three years of zero-Covid restrictions may have lowered people’s normal levels of immunity to influenza-like viruses, Wang said, which could lead to a wave of infections in the winter months.
Ben Cowling, an epidemiologist at Hong Kong University, told Reuters: “It is just a relatively large seasonal surge, perhaps partly due to chance and partly because there’s a bit of ‘immunity debt’ from the lesser winter surges in the last three years”.
State media has acknowledged the increase in pneumonia infections among children but stressed that most cases are mild and that parents should follow measures to reduce the risk of cases spreading, such as vaccinations if necessary, regular hand-washing, mask-wearing and staying at home when ill.
Additional research by Chi Hui Lin