A recent surge in respiratory illnesses — primarily in children — in China has drawn attention from the World Health Organization (WHO)Trusted Source, other health experts around the globe, and Western media.

In mid-November, China’s National Health Commission announced a significant rise in influenzasevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2)Mycoplasma pneumonia (a bacteria that causes pneumonia), and respiratory syncytial virus (RSV).

The country’s health authorities attributed the surge to an easing of China’s long, stringent COVID-19 restrictions and the normal cycle of cold and flu season. But given similar headlines that started appearing in late 2019, before the pandemic became global the following spring, the news has raised alarm.

Should you worry about China’s respiratory illness surge?

Many experts suggest that this is a normal response to the lifting of COVID restrictions, which can create a scenario where the general population’s immunity becomes more vulnerable to other common respiratory infections.

Dr. William Schaffner, a professor of preventive medicine specializing in health policy and infectious diseases at the Vanderbilt University School of Medicine, told Healthline that while the headlines may seem familiar, there’s no immediate cause for alarm.

“Initially, everyone was wondering whether they had seen this movie before, right? But the World Health Organization has had a virtual meeting with the Chinese scientists and infectious disease folks and I think left that meeting reassured that first of all, there is no new novel, strange virus, such as COVID,” Schaffner said.

“What the Chinese authorities have said is that consequent to their opening things up and coming out of lockdown, they are having an experience which was similar to the experience that we in the United States and the Western world had last year. Their lockdown lasted longer.”

Schaffner pointed out that respiratory disease in the U.S. also rose as people stopped social distancing after the peak of the COVID-19 pandemic. “We had early and very brisk influenza, and similarly RSV infections, and we had COVID also increasing,” he said.

How ‘immunity debt’ may play a role

The concept of “immunity debt” — in which social distancing, masks, and lockdowns weaken a population’s resistance to other pathogens — is a common theory behind China’s surge.

“The term ‘immunity debt’ or ‘immunity gap’ has been employed to describe this phenomenon, but this really just means that we are more susceptible to viruses we have not seen for a few years because we don’t have any immunity to them,” Dr. Monica Gandhi, MPH, a professor and director of University of California San Francisco’s Bay Area Center for AIDS Research, told Healthline.

“We saw a severe influenza season in Australia during our summer of 2022 (their winter), which was mirrored by our severe influenza and RSV season last winter in the Northern Hemisphere (especially among children).”

2022 study in England suggested that the “unprecedented suppression of RSV activity during winter 2020–21 is likely to have resulted in a large cohort of immunologically naive children younger than 5 years who have not been exposed to natural RSV infection but who became exposed upon the lifting of restrictions.”

Could China’s pneumonia outbreak spread?

In the short term, it appears unlikely that these respiratory illnesses could develop into a novel virus that becomes a global pandemic.

The combination of China’s extended lockdown, the expected “immunity debt” that resulted, and the country’s size are all factors that have to be considered as a reason for the current outbreak.

Additionally experts pointed out that most cases have only been reported in northern China, so we can expect to see more reported surges of these illnesses as people travel throughout the country.

“China is a big country. So this phenomenon may occur repeatedly in different parts of the country; the whole country is not experiencing this simultaneously,” Schaffner said. “As far as we know, this is happening mostly in northern China, is my understanding. So we may get a repeat of this in other parts of China as the weeks go by.”

The number of pneumonia cases in children are certainly alarming, but context has to be considered, Gandhi said.

“It is biologically plausible, given the almost three years of lockdown and avoidance of other pathogens in the country, that the immunity debt in China would be worse than in other countries, leading to this wave of pneumonias,” Dr. Gandhi said.

Can respiratory illness spread by air travel?

Schaffner acknowledged that respiratory infections can easily be exchanged between different populations through travel but cautioned that there’s not any indication of accelerated risk.

“Any virus — influenza, for example — can be carried by travelers from one place to another. But at the moment, the Northern Hemisphere, we in the United States, for example, are seeing a somewhat early increase in our own influenza, so we don’t need external importations,” he said.

“We’ve got plenty already. And our season is starting to take off.”

Takeaway

China’s surge in respiratory illnesses, especially pneumonia among children, is most likely a result of the country’s extended COVID-19 lockdown, which was longer than any other country in the world.

“Immunity debt,” the phenomenon in which a population’s susceptibility to certain pathogens and viruses increases from measures like social distancing, masking, and lockdowns, is the most viable explanation for the surge in these illnesses. There’s little reason for other countries to worry that this points to another global pandemic, experts say.

By Finn Maguire Cohen

Source: Healthline Media

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