Surge could be due to ‘immunity debt’, in turn caused by many pandemic restrictions that prevented exposure to other respiratory viruses
iStock photo for representational purpose China has set at rest fears surrounding its recent outbreak of a mysterious pneumonia-like illness and informed the World Health Organization (WHO) that there has been a general increase in respiratory illnesses due to multiple known pathogens in some parts of the country.
The Chinese government claimed there was no detection of any unusual or novel pathogens or unusual clinical presentations, including in Beijing and Liaoning. Since mid-October, the region reported an increase in influenza-like illnesses compared to the same period over the last three years, the WHO indicated previously.
Chinese health authorities blamed the increase in outpatient consultations and hospital admissions of children on Mycoplasma pneumoniae since May, and respiratory syncytial virus (RSV), adenovirus and influenza virus since October.
They, however, admitted that the rise in cases is being seen earlier than usual in this season, but claimed this was not unexpected given the lifting of COVID-19 restrictions. Among the winter-spring seasonal peak during 2014-2018, in northern China, there was an increase in influenza activity from December to May, according to a Nature study.
The authorities pointed out that other countries had a similar experience after COVID-19 restrictions were stopped, during a teleconference with the WHO on November 23, 2023.
Surveillance data provided by the National Influenza Centre in China to the WHO’s FluNet revealed that influenza-like illnesses (ILI) exceeded usual levels for this time of the year and are increasing in the country’s northern provinces. The viruses identified commonly were of A (H3N2) and B/Victoria lineage.
According to WHO’s risk assessment, there is not enough information available to characterise the overall rise in cases of respiratory illnesses seen in children.
On November 22, the WHO asked China for additional epidemiologic and clinical information, as well as laboratory results from these reported clusters among children, through the International Health Regulations mechanism.
Speaking to Down to Earth in a previous article, Amesh Adalja, an infectious disease specialist and senior scholar at the Johns Hopkins Center for Health Security, United States, pointed out that China lifted restrictions later than all parts of the world, which could be playing a role now in the fresh outbreak of respiratory illnesses.
Adalja recalled that a similar episode was reported in the US last year with simultaneous high rates of COVID-19, RSV and influenza.
Michael Osterholm, director of the University of Minnesota’s Center for Infectious Disease Research and Policy attributed this surge to an immunity debt, which could be the result of many pandemic restrictions that prevented exposure to other respiratory viruses, Fortune Magazine reported.
Responding to China, the WHO recommended vaccines against influenza and maintaining appropriate social distancing from people who are ill, getting tested and medical care as needed, wearing masks as appropriate; ensuring good ventilation, and practicing regular hand washing.
WHO advised against any travel or trade restrictions, except in the case of people with symptoms. Should people fall ill during travel or afterward, they are advised to get medical help and share their travel history with their healthcare provider.
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