Why You Shouldn’t Be Panicking About Pneumonia Outbreaks

The reemergence of childhood pneumonia and mycoplasma pneumonia in China and elsewhere is no COVID-like crisis but a return to post-pandemic normal.

Over the past several weeks, you might have noticed a flurry of ominous headlines about “mysterious” or “unusual” outbreaks of childhood pneumonia and/or “white-lung syndrome” in China, Europe, and even here in the U.S. — with some of the coverage suggesting the outbreaks are linked and that there may be a new novel pathogen on the loose like there was when COVID emerged four years ago. On Friday, a group of Senate Republicans even went so far as to call for a ban on travel to the U.S. from China in light of the reports. According to public-health officials and infectious-diseases experts, however, the outbreaks are neither mysterious nor unexpected but rather represent another return to post-pandemic normal when it comes to ebb and flow of respiratory-illness cases. Below, a look at the outbreaks and why there is definitely no reason to panic.

What’s happening in China?

Since the middle of October, there has been a surge of flulike respiratory illnesses in northern China, including a significant increase, compared with previous years, in the number of respiratory illnesses — such as pneumonia — among children. There have also been reports of hospitals in northern China being swamped with pediatric admissions, prompting Chinese health authorities to ask parents to avoid bringing children with mild illnesses to large hospitals and first seek treatment at other health-care facilities. There has also been a reported increase, over several months, in pediatric cases of mycoplasma pneumonia, which is caused by a lung infection from the antibiotic-resistant bacterium Mycoplasma pneumoniae.

The reports prompted the World Health Organization to send China an official request for data about the surge. Chinese health authorities said in response that, in effect, the surge was nothing to worry about — explaining that they had not detected any novel pathogens but were rather detecting a range of known respiratory diseases among children, including RSV, bacterial infections, the flu, and the common cold. Chinese authorities linked the rise to the reemergence of the various illnesses following the end of COVID restrictions in the country, which were finally lifted late last year. This has been, in other words, what happens when seasonal germs and non-COVID respiratory diseases get the chance to bounce back following the end of China’s zero-COVID policy.

China has hardly been transparent or cooperative with the world in the past about new respiratory illnesses circulating in the country, and Chinese officials notoriously attempted to hide and downplay COVID cases after the novel coronavirus first emerged there in late 2019 and early 2020. In this case, however, there is no evidence to suggest something similar is happening now. Per the Associated Press:

Dr. Paul Hunter, a professor of medicine at Britain’s University of East Anglia, doubted the wave of infections was sparked by a new disease. “If it was (a new disease), I would expect to see many more infections in adults,” he said in a statement. “The few infections reported in adults suggest existing immunity from a prior exposure.” Francois Balloux of University College London said China was probably experiencing a significant wave of childhood infections since this was the first winter since lockdown restrictions were lifted, which likely reduced children’s immunity to common bugs.

What is mycoplasma pneumonia, and where — and why — is it on the rise?

There have been reported increases in recent cases of childhood mycoplasma pneumonia not only in China but Singapore and several countries in Europe (Denmark, Sweden, Switzerland, France, and the Netherlands). There have also been a handful of recently reported cases in one county in Ohio.

The Mycoplasma pneumoniae bacterium that causes this lung infection is typically spread by respiratory droplets, and it’s often the cause of what is known as “walking pneumonia,” which has its name because it’s a typically mild illness. The bacterium is also more resistant to antibiotics than other strains that can cause pneumonia. That means the typical go-to antibiotics used for bacterial pneumonia (like amoxicillin) won’t be effective against mycoplasma infections, but other antibiotics (like azithromycin) should still work. As one epidemiologist recently summed up for Nature, antibiotic resistance may be one of the reasons children in China have been hit harder by mycoplasma pneumonia this year than kids in other countries post-pandemic:

Although pneumonia caused by the bacterium is usually treated with antibiotics known as macrolides, an overreliance on these drugs has led to the pathogen developing resistance. Studies show that resistance rates of M. pneumoniae to macrolides in Beijing are between 70% and 90%. This resistance might be contributing to this year’s high levels of hospitalization from M. pneumoniae, because it can hinder treatment and slow recovery from bacterial pneumonia infections, says [Benjamin Cowling, an epidemiologist at the University of Hong Kong].

And a new study published last month in The Lancet Microbe reported that the bacterium is now staging a comeback around the world following a decline in detected cases owing to COVID restrictions but noted that “in countries where M pneumoniae has re-emerged, case numbers are comparable to pre-pandemic (endemic) numbers.”

We can now confirm the re-emergence of M. pneumoniae in many countries. We anticipate the most recent data collection for the ESGMAC MAPS study to be online for early December 2023. pic.twitter.com/qHRUPJBbZt

— Mike Beeton (@mike_beeton) November 23, 2023

Adds University College London’s Francois Balloux in an X thread:

Mycoplasma pneumoniae infections happen all year round with a peak in winter. There is also a ~3-7 year periodicity, with a bigger epidemic roughly every ~4 year. This pattern predates the Covid-19 pandemic and has been observed over the past decades.
2/https://t.co/4b0CcgskgZ pic.twitter.com/T2kAWBjQav

— Prof Francois Balloux (@BallouxFrancois) December 1, 2023

First, circulation of Mycoplasma has been reduced during the pandemic and hence fewer people, in particular young kids, have acquired immunity to it over the last 3.5 years.
4/

— Prof Francois Balloux (@BallouxFrancois) December 1, 2023

Second, the last big wave of Mycoplasma happened 4 years ago in the 2019/2020 winter. Thus, as Mycoplasma pneumoniae epidemics tend to peak about every fourth year, we might have been up for a big wave this winter, even in the absence of the Covid-19 pandemic.
5/

— Prof Francois Balloux (@BallouxFrancois) December 1, 2023

Though the vast majority of mycoplasma infections don't require treatment with antibiotics. Drug resistant mycoplasma can make rare, severe cases hard to treat, but drug resistance doesn't make it more transmissible or virulent, and it is not to blame for the current wave.
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— Prof Francois Balloux (@BallouxFrancois) December 1, 2023

What’s happening in Ohio and Massachusetts?

Health authorities in Ohio’s Warren County recently reported an outbreak of 145 cases of childhood pneumonia beginning in August without any resulting in severe illness or death. In some of those cases, mycoplasma was detected, but the Ohio outbreak has not been linked to the one in China or any other ones abroad.

Meanwhile in Massachusetts, what local health officials describe as a typical seasonal increase in pediatric pneumonia has been erroneously reported as another U.S. outbreak, as the Washington Post explains:

Widespread media coverage of a pneumonia spike in western Massachusetts was dispelled Friday by pediatrician John Kelley, whose comments to a local news outlet about how children with RSV sometimes develop pneumonia were inaccurately reported as confirmation of a second outbreak. Kelley told The Washington Post he is not seeing unusual pneumonia trends or any parallels to China in his office. Massachusetts health officials said a statewide increase in pediatric pneumonia is expected this time of year, with no evidence suggesting a link to mycoplasma.

The CDC said on Friday that it is monitoring the increases in respiratory illnesses around the world and reported that the current rates of pediatric pneumonia in the U.S. are roughly similar with previous years’.

“White-lung syndrome” isn’t really a thing.

Some of the coverage of the recent childhood-pneumonia outbreaks has described the illness as “white-lung syndrome.” As Stanford infectious-diseases doctor Jake Scott emphasized in an X thread on Friday, white lung is a “made-up term” — which public-health authorities never use — that just literally describes what the lungs of anyone with pneumonia or some other respiratory illnesses look like when seen on an X-ray or a CT scan:

“White lung syndrome” is a made-up term. Any pneumonia appears as a white opacity on an x-ray or CT, which is partly how the diagnosis of pneumonia is made. But it’s not specific to pneumonia, and it’s certainly not specific to Mycoplasma pneumoniae, which is not “mysterious”. Mycoplasma pneumoniae is a bacterium, not a virus. (It’s one of the smallest free-living organisms.) It can cause pneumonia in kids age 5-17 and can be severe but is very uncommonly fatal. Radiographic findings vary but can look worse than anticipated from the physical signs … Making up scary terms to describe infectious diseases we’ve been dealing with for a long time doesn’t help anyone. It just causes confusion and anxiety. And it causes doctors like myself a headache.