COVID-vaccine-induced myocarditis occurs less often than febrile seizures do after the measles, mumps, and rubella vaccine (about one in 2,500 doses), but more often than a bruising condition called immune thrombocytopenia purpura (one in 30,000). The myocarditis cases are also more common than cases of anaphylaxis after the Hepatitis B vaccine (one in 1.1 million), which is required for elementary schoolers in all but a handful of states.

But the rate of COVID-vaccine-induced myocarditis doesn’t tell us that much on its own. “The question is, how severe is myocarditis?” says Daniel Salmon, who directs the Johns Hopkins Institute for Vaccine Safety. We still don’t really know. According to the CDC, most patients with post-vaccine myocarditis “felt better quickly,” and “can usually return to their normal daily activities after their symptoms improve.” But no one can say yet whether a bout of vaccine-induced myocarditis now would harm someone’s health in a year, or 10 years, or 50. Salmon told me he wouldn’t support a kids’ mandate until researchers are able to rigorously follow kids who get myocarditis for a year or two, and find no related serious health problems.

Waiting a year or two would also give regulators a chance to see how Americans learn to live with SARS-CoV-2 as an endemic virus, which has its own implications for any potential mandates. Lainie Ross, a pediatrician and bioethicist at the University of Chicago, told me that right now, “what makes this disease unique is that everybody is sort of a virgin” to the virus that causes it. If it doesn’t continue to transform into new and more dangerous variants, and if the vaccines (or natural immunity left by previous infections) remain protective against it, then COVID-19 will likely start to resemble measles or chicken pox: It will become a childhood disease, because every living adult will already have been exposed. That makes the case for childhood mandates much easier.