Since the beginning of autumn, the pediatric outpatient clinics of children's hospitals and general hospitals in many places across the country have ushered in a peak of visits, and even the number of individual daily visits has exceeded 10,000. As of November 26, 2023, the monitoring data released by the National Influenza Center of China shows that the positive rate of influenza virus tests in southern and northern provinces has continued to rise this week, and all regions have entered the season of high incidence of respiratory infectious diseases.
The menacing wave of childhood pneumonia in China has attracted global attention. On the 27th of last month, the top journal Nature focused on the situation of "the surge of respiratory diseases in Chinese children" and published the title "what's behind China's mysterious w**e of childhood pneumonia?".**.
WHO: is a common winter infection.
It's not that a new virus has emerged.
In fact, as early as last week, the World Health Organization (WHO) made it clear that the surge in hospitalizations in China was not caused by the emergence of "new" pathogens, but by common winter infections.
This winter has been a "very unusual" one for our country – the first since the pandemic began in 2020 that no containment measures have been implemented. Epidemiologists said that although the number of infections was expected to surge in the winter, the high incidence of pneumonia in China this time was somewhat unexpected.
In the past, influenza and respiratory syncytial virus (RSV) would be the main reasons for the surge in infections.
In line with projections, data released by China's health authorities show that the surge in hospitalizations since October is largely due to known pathogens such as adenovirus, influenza virus and RSV, although RSV tends to cause only mild cold-like symptoms.
Unexpectedly, mycoplasma pneumoniae has been the main cause of hospitalizations of large numbers of children since May, especially in northern cities such as Beijing.
As a microorganism that infects the lungs, Mycoplasma pneumoniae is common in "walking pneumoniae"**. The so-called "walking pneumonia" is actually a mild form of pneumonia that many children only cough but does not affect their lives, and does not need bed rest or hospitalization**. But it is such an insignificant Mycoplasma pneumoniae that has dealt a big blow to children this winter.
Benjamin Cowling, an epidemiologist at the University of Hong Kong, is not surprised by the wave. He said it was a typical "winter outbreak" of acute respiratory infections. "Compared to usual, this year's onset time is indeed slightly earlier. This may be due to the increased susceptibility to respiratory infections as a result of the three-year-long Covid measures. ”
Source: Nature (Costfoto Nurphoto via Getty).
The reason behind the wave of infections is:
Immunization Debt?The Nature article mentions that this wave of infections in China is not accidental, but more like a "familiar pattern".
In fact, many other countries saw a trend of common respiratory illnesses in the first winter after COVID measures such as mask-wearing and travel restrictions were lifted. For example, in November 2022, the number of flu-related hospitalizations in the United States hit a record high since 2010.
Francois Balloux, a computational biologist at University College London, uses the term "immunity debt" to describe this phenomenon. He said that national lockdowns or other measures imposed by the state to slow the spread of the coronavirus have also stopped the spread of seasonal pathogens, leaving people with little chance of building immunity to these microbes, a phenomenon known as "immune debt."
In fact, immunization debt is not a new concept, it was first proposed by French researchers in August 2021, arguing that due to the long-term "low exposure to pathogens", the proportion of susceptible people is increasing, and the likelihood of future epidemics increases. Among them, children born during the epidemic also face a more serious problem of immunization debt.
doi: 10.1016/j.idnow.2021.05.004.
Over the past three years, the world has set off rounds of anti-epidemic campaigns, wearing masks, washing hands frequently, social distancing, and online classes. Thanks to a combination of containment measures, respiratory viral infections that are usually prevalent during the winter months have all but disappeared. But the virus will not go away, with the end of the new crown epidemic and the collective removal of masks, a new round of counterattack of other viruses is inevitable, especially in children and immunocompromised people, it is only a matter of time and degree of infection.
Regarding the "explosive" ** Balloux in China this time, he said: "China has experienced almost the longest and strictest epidemic prevention in the world, so the wave of infections after the epidemic is opened up will be much more serious." ”
Antimicrobial resistance may be another explanation.
However, the wave of disease experienced in China is not exactly the same as in other countries – many countries are grappling with influenza and RSV infections in the post-pandemic winter, but Mycoplasma pneumoniae is more common in China. "It's really surprising," Cowling says, "because bacterial infections are often opportunistic and tend to develop after a viral infection." ”
But there's another explanation: drug resistance.
Typically, the most important drug for Mycoplasma pneumoniae pneumonia is a macrolide antibiotic. However, due to the over-reliance on antibiotics, pathogens have developed resistance.
Data show that the resistance rate of Mycoplasma pneumoniae to macrolides in Beijing is as high as 70-90%. Cowling said this high level of drug resistance is also one of the likely reasons for the high rate of hospitalizations caused by Mycoplasma pneumoniae this winter, which can hinder the progression and slow recovery from infection.
Christine Jenkins, a respiratory physician at the University of New South Wales in Australia, stressed that winter disease outbreaks are always a serious challenge, but the current Chinese healthcare system has been able to cope with and mitigate the epidemic better than before the new crown. "Currently, China has a better national disease surveillance system, diagnostic tests, and measures to stop transmission and prevent deaths. ”
Jenkins added that even infections caused by known pathogens must be closely tracked to minimize the risk of widespread outbreaks. "Although the current situation is far from the coronavirus, it is still not to be taken lightly. ”
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