I couldn't help thinking, as I channel-surfed through various college football, golf, and other sporting events on Saturday, that COVID-19 disease rates will see another significant spike in the coming weeks. I hope I'm wrong. Hand-wringing aside, I wanted to mention a couple issues that you might have missed this past week.
MISC-C Long-term Followup
I fall into the glass half full crowd when I read this report on 1 year follow-up data for 68 children in England. No deaths occurred and only 2 children required critical care readmission. Fourteen of 19 children with coronary aneurysms had resolution and all 39 with abnormal function but no aneurysms had returned to normal echocardiograms. Yes, I know it's just a few patients, but given how sick most of these kids are at the start I'm encouraged.
The Rule of 3's
This month could see data submitted to FDA requesting authorization for COVID-19 vaccines for children under 12 years of age. Because these trials are "immunobridging" studies, the key data in addition to safety are whether the immunologic responses are similar to those seen in adolescents and young adults who showed protection from infection in the larger efficacy trials.
Speaking of safety, you all have probably heard that FDA requested additional children ages 5 through 11 years to be enrolled in the mRNA trials. I was puzzled by this because the myopericarditis rates seen so far are pretty low, about 10 excess cases per million vaccine doses in a recent article. It would require an impossibly large number of children in a research trial to detect this, so I was even more surprised to hear FDA's Peter Marks state that the FDA was following the rule of 3's in trying to assess safety of these vaccines for serious adverse events. This rule is explained in an oldie but goodie review article in JAMA stating that, if no events occurred in n subjects we can be 95% confident that the highest chance of this event is 3/n. The number of subjects in these current trials are in the few thousands, so if the logic behind adding a few more is to satisfy cardiac inflammatory risk concerns the addition of a couple thousand more subjects probably won't answer the question. It may allow some reassurance that the rate isn't substantially higher than what is being seen in adolescents and young adults.