Pneumonia clusters among children in China. A new disease, or a bunch of old ones?

Photo credit: Tang Ming Tung, Getty Images

There are reports of an uptick in cases of pneumonia in parts of China, especially among children. The WHO has asked for more information, and experts are watching. An email from ProMED seems to have kicked off initial interest. Here’s the initial report, followed by my impressions of what we might be dealing with here:

Is this the next Covid-19?

It’s too early to know if this is the dawn of some new pandemic. However, initial reports are actually reassuring, including an updated statement from the WHO released yesterday. While we don’t want to ignore genuine threats, the most common theory among experts—and what makes sense to me, so far—is currently this: the likely explanation is not a new infectious pathogen (like SARS-CoV-2, the virus that causes Covid-19 was). Rather, this looks like “catch-up” phenomenon; that is, after several years of pursuing “Zero Covid,” China finally opened things up late last year. So, the fall of 2023 is the first respiratory virus season without intense infection control measures in place there. Accordingly, there’s a cohort of young children who never got a bunch of seasonal pathogens for a few years who are therefore “immune naive” to them. Thus, common pathogens that cause children to get, say, 2-3 colds per season (or even the occasional pneumonia) that were not around in 2020-2022 are now circulating in a population with little-to-no immunity to them. It follows, then, that children in China might expect an onslaught of viruses and bacteria that cause respiratory illnesses this year, and earlier in the season than usual—just as we experienced major (and earlier-than-usual) upticks in RSV in the US after we let our guard down with measures taken to slow Covid down.

What we know about severity.

So far, the descriptions of these illnesses sound unpleasant but not routinely life-threatening. The need for hospitalization for a pediatric respiratory illness often reflects reasonable concern by clinicians, as opposed to the clear need for advanced life-saving treatments (ICU level of care) that adult hospitalizations usually imply. The need for “IV drips” mentioned in the ProMED report, for example, might strike you as a proxy for severity. But often that isn’t so. We give medications by IV for many reasons—including for patients with substantial nausea or vomiting; you’ll often see kids being given by IV medications because they are dehydrated, or need a routine drug that would be just as effective given by mouth, if that were possible.

What we are not hearing so far are reports of loads of kids ending up on respirators, ICUs, or worse. Of course, that could be because the risk is low enough and we haven’t seen enough cases. The law of large numbers can deceive us. A disease that causes 1 in 5,000 infected kids to require a breathing machine might lead to a just a handful of severe cases in a decent-sized city. But if 25 million kids get that pathogen, you’d suddenly be looking at 5,000 kids on ventilators—which would be scary.

So what’s causing this outbreak in China?

People keep using the word “mysterious” or “undiagnosed.” While that might sound a little anxiety-provoking, we should also remember that most respiratory illnesses including pneumonia are never “officially” diagnosed with a specific viral or bacterial cause. Sure, we test for Covid, RSV, flu, and other bugs. And we should be doing more of that. But it’s not unusual for clinicians and public health officials to not know what is behind a cluster here or there (or to later find out that the cause was a usual suspect, rather than a new threat. So, I don’t put too much stock in the fact that we don’t know the cause of these outbreaks with any certainty yet.

That said, RSV, influenza, Covid-19, and mycoplasma pneumoniae are known quantities which we are we’re hearing about from those monitoring the China situation. Mostly, RSV and influenza cases are treated with supportive care, though some specific treatments can be useful in certain groups. Mycoplasma can cause lots of misery, from ear infections to pneumonia (mild “walking pneumonia,” usually, but sometimes more severe), and is typically treated with an antibiotic like azithromycin. There has been some speculation about antibiotic-resistant mycoplasma being behind some of this. While not substantiated, I will add that this is a good reminder to clinicians not to over-prescribe antibiotics. Resistance is real, and can (and will) cause problems for us.

But it seems like some of the explanation for why China is currently detecting more mycoplasma than usual is that they’re now testing for that disease more widely than they have in the past. This is called detection bias; you can’t diagnose something you don’t test for. That said, given how busy medical clinics and hospitals are in China right now, it’s probably more than just increased surveillance. It’s probably increased prevalence too.

My house is also a viral hotspot.

One of my two kids is five years old and just started in a new school this fall. For several years, she attended a preschool where they had excellent mitigation measures in place; First, there was lots of outdoor time; Then there were masks (somehow, my toddler learned to read prior to Kindergarten and became a little person with great empathy, despite all the anti-mask panic we all heard) and testing; Then there were lots of open windows and excellent ventilation, which was nice when the preschool dropped those masks; She basically never got sick. A preschooler, mind you! Now she is in a more crowded school environment and surrounded by new kids with different immune histories. She has been sick off-and-on for around 6-7 weeks now. There have been several distinct viruses/bouts (rather than one long protracted “thing”). It sucks.

All to say that if what is happening in my home is a microcosm of what is going on in China now, it’s bound to be a slog of misery, leading to more healthcare use than would be typical—including sick visits to the doctor, and some oral medications. But that’s the extent of it (for the most part). Hopefully, it’ll remain that way in China, and in my home.

While these last weeks have not been fun in my house, part of me is glad this is happening now that my daughter is five, rather than earlier in her life. Her airways are bigger, and her body is sturdier than when she was a baby or a toddler. My hypothesis is that if she’d gotten these bugs earlier in life, they would have been more spread out in time, yes, but perhaps a bit more serious each time. Would any of them have landed her in a hospital for a couple of days? Possibly. We’ll never know. Covid mitigation seems to have delayed my kid getting a bunch of seasonal illnesses until she was older and, frankly, more robust. Time, it turns, out, is a kind of vaccine.

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