Could be part of it. Another factor is isolation prevented kids from being exposed to the usual suite of early childhood illnesses and developing robust immune systems.
It also may not be out of the blue, but out of Wuhan. It could be that the Chinese realized that we don’t revere the elderly as much as they do and decided to try something that infects children preferentially.
It isn’t out of Wuhan.
Bejing and Lioning
UNDIAGNOSED PNEUMONIA - CHINA (04): (BEIJING, LIAONING) CHILDREN, REPORTED EPIDEMIC
https://promedmail.org/
Date: Thu 23 Nov 2023 09:08 EST
Source: BBC [edited]
https://www.bbc.com/news/world-asia-china-67505218
China has reported no “unusual or novel pathogens” in clusters of child pneumonia cases, the World Health Organization (WHO) has said. Beijing has attributed a rise in flu-like illnesses to the lifting of COVID-19 curbs, said the WHO, which had requested for more data on the cases. Still it urged residents in China to take precautions, like getting vaccinated and wearing masks. Local media had in recent days reported hospitals being overwhelmed.
In a statement on Wednesday [22 Nov 2023], the WHO said it requested China for more information on reports in the media and from ProMED — a global outbreak surveillance system — of “clusters of undiagnosed pneumonia in children in northern China.” Pneumonia is a general medical term used to describe an infection and inflammation of the lungs. It can be caused by many different viruses, bacteria or fungi.
After the WHO’s request, state-run Xinhua news agency published an article which quoted officials of China’s National Health Commission (NHC) as saying they were paying close attention to the diagnosis and care of children with respiratory illnesses.
Later on Thursday [23 Nov 2023], the WHO said in a statement that China has not detected any “unusual or novel pathogens,” and that the increase in respiratory illnesses spreading in the north of the country was due to “multiple known pathogens.” Since October 2023, northern China has reported an “increase in influenza-like illness” compared to the same period over the past 3 years, the WHO said. “Some of these increases are earlier in the season than historically experienced, but not unexpected given the lifting of COVID-19 restrictions, as similarly experienced in other countries,” the statement said.
The WHO said it is “closely monitoring the situation and is in close contact with national authorities in China”. While mentions of China and a wave of infection can get people jittery as it brings memories of the COVID-19 pandemic, it is good practice for the WHO to ask for clarity.
(excerpt) Multiple reports at link
I doubt that the Chinese did this intentionally. They seem to be the first to suffer and with the most severe effects.
I would follow a variation of the idea, that the Chinese are still screwing around with bioweapons research and something else really nasty escaped from their labs. Again.
I have worked in Taiwan. They are not very good at facilities maintenance. It is even worse in mainland China.
But I note that unsanitary Chinese agricultural practices with pig and chicken production is commonly understood to be the breeding ground for every new annual version of the Flu virus and has been so for a very long time. No clever bioweapons research is needed.