COVID and Streptococcus

Over the last few months, there has been quite the internet kerfuffle about whether COVID infections result in a subsequent susceptibility to other infections (I’m trying to avoid some of the terminology used because it often has been used very imprecisely). I’ve been on the fence: the RSV data from several countries suggests that, for RSV, its severity has risen post-COVID, but there are other straightforward explanations for other pathogens such as influenza (lack of exposure and lower vaccination rates).

With that as prelude, there’s a recent study from Israel that compared various long COVID-related symptoms in people who were and were not infected (the uninfected provide a baseline as a control). Here’s what they found, and for this post, focus on the panel that has streptococcal tonsilitis:

Until seven months after infection or so, those who have been infected, have a 10%-30% higher rate of streptococcal tonsilitis–and that peaks at around four months. This is not a case of a higher risk for a few weeks after infection, which is well known (and not surprising) for multiple pathogens.

Mind you, that’s the relative increase for all people in streptococcal infections. Here’s how it breaks down by age–and the significant effects are found in children (boldface mine):

In the 12-18 years subgroup (supplementary tables S4c and S4i), streptococcal tonsillitis remained significantly high during early and late phases (early: hazard ratio 1.68 (1.40 to 2.02) and risk difference 37.4 (21.5 to 53.3); late: 1.55 (1.33 to 1.81) and 57.3 (33.2 to 81.4) respectively) whereas anosmia and dysgeusia (hazard ratio 23.50, 5.48 to 100.86; risk difference 15.6, 10.1 to 21.0), dyspnoea (1.70, 1.36 to 2.12; 32.4, 17.9 to 46.8), and weakness (1.66, 1.41 to 1.96; 55.2, 35.7 to 74.7) were significantly high during the early phase only.

In the 5-11 years subgroup (supplementary tables S4b and S4h), streptococcal tonsillitis was significantly higher during early and late phases (early: 1.25 (1.15 to 1.36) and risk difference 50.7 (17.9 to 83.5); late: 1.12 (1.05 to 1.21) and 50.0 (−1.5 to 101.5), respectively), whereas risk of conjunctivitis was significantly higher in the early phase (hazard ratio 1.24, 1.07 to 1.43; risk difference 35.7, 9.1 to 62.3) and sore throat during the late phase (1.54, 1.20 to 1.97; 29.7, 10.5 to 48.9).

In the youngest 0-4 years age group (supplementary tables S4a and S4g), we observed elevated risk for conjunctivitis (hazard ratio 1.18, 1.08 to 1.29; risk difference 147.3, 51.3 to 243.3) and dyspnoea (1.22, 1.11 to 1.35; 121.9, 47.8 to 196.0) only during the early phase.

So parents with elementary school-aged kids, you might not be imagining things. Depending on their age, kids who have had COVID are roughly 50% more likely to get streptococcal tonsilitis according to this study.

The good news is that this elevated risk in kids isn’t very high in absolute terms: it’s around 0.5%*. That said, the absolute effect averages across seasons; if the increase is concentrated at certain times of the year, that ‘surge’ will be difficult to handle. From a public health perspective–in particular, keeping hospitals from being overwhelmed–is that “1-most” (which is the percentage of sick kids) is very dependent on the size of most: small changes in the likelihood of illness can overwhelm hospital capacity, even though most kids will still be fine (not require hospital treatment).

It’s also unclear how general this effect is. Is it a few kids who are very susceptible or a more general modest increase in susceptibility? We also don’t know if this applies to other respiratory infections. Unfortunately, they don’t have data for RSV or influenza, though those weren’t very common during much of the study period.

From a policy perspective, if we’re de facto going to ‘lie back and think Biden’**, which is to say, tolerate having multiple COVID infections every year, we should consider a rise in childhood infectious diseases to be very possible. It’s not TEH AIDS!!, but it very well could make a lot of other things worse.

*I think the sample sizes are too small, but vaccination doesn’t appear to do much in this case.


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