How China's COVID Restrictions Led to Disease Rampage: 'Immunity Gap'

China is facing a significant upsurge in respiratory illnesses, particularly among children, with experts attributing the unusually large seasonal outbreak to an "immunity gap" created by the country's yearslong fight against COVID-19.

Li Tongzeng, the chief physician of Beijing You'an Hospital's infectious disease department, told China's state-backed Global Times newspaper on Monday that lowered antibody levels, particularly in young patients, were a consequence of reduced exposure to pathogens during the pandemic.

The Chinese government maintained some of the world's strictest anti-virus measures for almost three years between late January 2020 and early December 2022. To prevent the spread of SARS-CoV-2, the virus responsible for the disease, adults and especially children were confined to their homes in lengthy lockdowns that necessitated the suspension of work and school.

The pandemic strictures, which gave way to continued mask-wearing, sanitizing and social distancing for large parts of this year, increased children's vulnerability to other infectious respiratory diseases besides COVID, according to Li's theory about China's "immunity gap."

Li told the Chinese tabloid that the infection rate this year had surpassed levels seen in the past three years.

A surge in respiratory illnesses followed Beijing's decision nearly one year ago to lift all anti-COVID measures overnight. The result—also observed in other countries, including the United States, but on an apparently smaller scale—appeared to be a release of various pathogens, contributing to the current strain on hospitals, especially in northern China.

At a press conference on Sunday, China's National Health Commission said the recently prevalent respiratory diseases were primarily influenza-related, with additional culprits including mycoplasma pneumonia, rhinovirus infections, respiratory syncytial virus, and adenovirus.

Huang Li-min, a pediatrician at National Taiwan University Children's Hospital, expressed concern about the constant mutation and drug resistance of mycoplasma bacteria in China, Taiwan's China Times daily newspaper reported on Monday.

While mycoplasma pneumonia is typically mild, in China there is high resistance to the front-line antibiotics used to combat that illness. Beijing, the capital, was already witnessing resistance exceeding 90 percent in the early 2010s, according to a peer-reviewed study published a decade ago.

In northern China, which appears to be experiencing the worst of the outbreak, respiratory infections have surged for five consecutive weeks, accounting for 6.2 percent of outpatient and emergency visits, at a rate 2.5 times the average of the past three years, Lo Yi-chun, the deputy director of the Taiwan Centers for Disease Control said on Sunday, citing World Health Organization data.

China's national health authority said different pathogens were more prevalent among different age groups: influenza and rhinovirus for 1- to 4-year-olds; mycoplasma pneumoniae and adenovirus for 5- to 14-year-olds; and influenza, rhinovirus and COVID for those 15 and up.

At the recent press briefing, health officials called on all localities in China to coordinate the use of medical resources, implement priority-based diagnostics and treatment protocols, and enhance the efficiency of identifying and referring severe cases.

The commission stressed the importance of opening relevant clinics, extending service hours, strengthening drug supply lines and incorporating traditional Chinese medicine.

Update 11/30/23, 1:00 p.m. ET: A previous version of this article said different age groups were listed as being susceptible to different pathogens. In fact, the list concerned the prevalence of pathogens among different age groups.