A commentary published last week in the medical journal Pediatrics reviewed a published account of seven cases of myocarditis in teen males following Covid-19 vaccination. The authors concluded that "there are some concerns regarding this case series that might suggest a causal relationship" between the vaccine and myocarditis. "There are some suggestions [the link] may be real, but it's not definitive yet," Dr. Sean O'Leary, a co-author of the commentary, told CNN.