Pneumonia is a lung infection that can cause fever, cough, difficulty breathing, and chest pain. It can be caused by various germs, such as bacteria, viruses, fungi, or parasites. Some types of pneumonia can be mild and treatable at home, while others can be severe and require hospitalization.
In recent months, both China and the US have reported an increase in pneumonia cases among children, raising concerns about a possible new or emerging pathogen. However, according to the World Health Organization (WHO) and independent experts, the outbreaks are likely due to a resurgence of common respiratory infections that were suppressed during the COVID-19 pandemic.
What is happening in China?
As reported in China Daily⁴, an increase of mycoplasma pneumoniae infections in China was observed in May 2023 by Zhou Huixia, director of a children’s medical centre, with a “rapid increase” in August and a “particularly ferocious” wave starting in early October. On 24 October 2023, Zhou predicted that the wave would peak in November.
Mycoplasma pneumoniae is a bacterium that infects the lungs and causes a form of pneumonia that is often referred to as “white lung syndrome” due to the fact it causes the lungs to appear white on X-rays. It is also known as “walking pneumonia” as it can be mild enough to allow patients to continue daily activities while unwell. However, it can also cause complications such as bronchitis, ear infections, or even encephalitis (brain inflammation).
The outbreak has mainly affected children in northern China, especially in Beijing and Liaoning province, where hospitals have been overwhelmed by the influx of patients. According to the WHO, China has reported more than 300,000 cases of mycoplasma pneumoniae infection in children since May, with a peak of over 100,000 cases in October
At a press conference on 13 November 2023, Chinese authorities from the National Health Commission attributed the increase in respiratory diseases in China to the lifting of COVID-19 restrictions and the circulation of known pathogens such as influenza, mycoplasma pneumonia, respiratory syncytial virus (RSV), and SARS-CoV-2 (the virus that causes COVID-19). Authorities stressed the need for enhanced disease surveillance in healthcare facilities and community settings, as well as strengthening the capacity of the health system to manage patients.
On 21 November, media and ProMED reported clusters of undiagnosed pneumonia in children in northern China. It is unclear if these are associated with the overall increase in respiratory infections previously reported by Chinese authorities, or separate events. On 22 November, WHO requested additional epidemiologic and clinical information, as well as laboratory results from these reported clusters among children, through the International Health Regulations mechanism. The WHO also contacted clinicians and scientists through its existing technical partnerships and networks in China.
What is happening in the US?
The US has also seen a surge in respiratory infections among children, particularly in Ohio and Massachusetts. The Warren County Health District in Ohio recorded an “extremely high number of pediatric pneumonia cases” since August, with 142 cases above the county average and meeting the department’s definition of an outbreak⁹. The average age of the children affected was around 8 years old and cases were found in several school districts. Symptoms included cough, fatigue and fever.
Some of the cases in Ohio were of mycoplasma pneumonia, the same illness that has been seen in outbreaks in China and Denmark. However, the health district stated that they do not think this is a new or novel respiratory disease, but rather a large uptick in the number of pneumonia cases normally seen at one time. They also said that there have been no conclusive patterns among the children diagnosed and that they are investigating the source and cause of the outbreak.
Eastern Massachusetts has also seen many cases of walking pneumonia, which is a mild lung condition that can develop from a respiratory virus called RSV. RSV is a common cause of bronchiolitis and pneumonia in infants and young children, and can also affect older adults and people with weakened immune systems. Symptoms include runny nose, cough, wheezing, and fever.
Dr John Kelley of Redwood Pediatrics in East Longmeadow told Western Mass News that this is the season for RSV and that they are seeing a lot of it. He said that RSV can cause lower viral respiratory infections, which can spread to the lungs and cause pneumonia. He advised parents to seek medical attention if their children have trouble breathing, are dehydrated, or have a high fever.
Is there a link between the outbreaks?
According to the WHO and independent experts, there is no evidence to suggest that the pneumonia outbreaks in China and the US are linked or caused by a new or emerging pathogen. Rather, they are likely due to a phenomenon of “lockdown exit” waves of respiratory infections, which is sometimes referred to as “immunity debt”.
This means that the global health measures implemented to slow the spread of COVID-19, such as lockdowns, mask-wearing, and travel restrictions, prevented seasonal pathogens from circulating, giving people less opportunity to build up immunity against these microorganisms. As the novel coronavirus abated and restrictions lifted, those pathogens vigorously returned.
This pattern has been observed in other countries, such as the UK and Australia, where the easing of COVID-19 measures was followed by a surge in respiratory infections, especially among children. Francois Balloux, director of the University College London’s Genetics Institute, said in a media statement that since China experienced a far longer and harsher lockdown than essentially any other country on Earth, it was anticipated that those “lockdown exit” waves could be substantial in China
The WHO recommended that people in China and the US follow measures to reduce the risk of respiratory illness, which include recommended vaccination; keeping distance from people who are ill; staying home when ill; getting tested and medical care as needed; wearing masks as appropriate; ensuring good ventilation; and regular hand-washing. The WHO also said that it will continue to provide updates on the situation.
Conclusion
In summary, the pneumonia outbreaks in China and the US are not caused by a new or novel pathogen, but by a resurgence of common respiratory infections that were suppressed during the COVID-19 pandemic. The outbreaks are mainly affecting children, who have lower immunity to these pathogens due to the lack of exposure during the pandemic. The outbreaks are not linked or related, but are part of a global phenomenon of “lockdown exit” waves of respiratory infections. The best way to prevent and treat these infections is to follow the recommended health measures and seek medical attention as needed.
