With the news that the FDA is likely to extend the Pfizer emergency use authorization to kids 12+ next week, I've been thinking about covid in kids. Pediatric covid deaths are extremely rare. Even adding in deaths from MIS-C, the inflammatory condition that can follow covid, there have only been about 300 kids in the US who have died from the virus, and serology data indicate that somewhere between a quarter and a third of US kids have antibodies from infection. That puts the fatality rate for kids around 20 per million infections. By comparison, for those 25-44, the fatality rate is about 3 per 1000 infections.
The fatality rate from covid for kids is still higher than the risk of severe reactions to the vaccine in adults. The main severe side effect for the RNA vaccines so far appears to be anaphylaxis, which is something that kids are more susceptible to than adults. I think vaccination still does make sense, as we are able to treat the anaphylaxis when it happens, but the therapeutic margin between benefit and side effect is smaller for kids.
Aside from death, the other possible negative consequence of covid for kids is the possibility of lingering symptoms. I did some searches for long covid and kids, and it appears that while kids are somewhat less likely than adults to get long covid, it is still not rare for them.
The UK recently did a large survey of self-reported symptoms consistent with long covid. They found that of those who had tested positive for covid, about 10% of the 2-11 age group and 12% of the 12-16 age group had symptoms 5+ weeks after diagnosis. By comparison, about 2.5% of kids who had not tested positive for covid had symptoms. This study did not break out details about the severity of symptoms in kids specifically, but I did find a study done in Italy that did.
The study in Rome, Italy involved interviewing the parents of 129 kids who had a prior positive covid test. About three-quarters had some symptoms initially, so symptomatic kids are definitely being over-represented here, but some of the kids who had been asymptomatic initially developed long covid symptoms later.
Of the 129, three had developed MIS-C, and two had myocarditis. About a quarter of those 2-3 months out and half 3+ months out had at least one long covid symptom. This is a bit strange. Most studies show long covid decreasing with time.
The persisting symptoms at 3+ months sound similar to adult long covid, with the most common complaints being insomnia, brain fog, headaches, muscle/joint pain, and diarrhea. It appears that kids are a bit less likely than adults to have altered smell, interestingly. At 3+ months, 9% of the kids were reported to have symptoms that caused them a lot of distress.
Neither of these studies was longitudinal, a type of study where individuals are followed over time. They simply asked people if they were willing to participate at one point in time. That means that the researchers may be getting people with more problems willing to volunteer. The study in Italy says that they enrolled all 129 kids who tested positive at one specific university testing center, though. I don't doubt that they were missing a lot of asymptomatic infections in kids, but at the same time, if half of kids are asymptomatic, the adjusted rate of kids who are in distress 3+ months later would be about 6%, going by the study in Italy. That study was small, and I would really like to see a larger study of lingering symptoms in kids, preferably one that follows them starting with diagnosis.
The thing we don't know is how long these long covid symptoms last. Some adults with long covid are reporting that they are feeling better 7 or 8 months later, but we don't have very good data on recovery, even in adults.
Study done in Italy: https://www.medrxiv.org/content/10.1101/2021.01.23.21250375v1.full.pdf
Guardian article interviewing parents : https://www.theguardian.com/society/2021/may/03/its-terrifying-parents-struggle-to-get-help-for-children-with-long-covid