The group searched the VAERS database for symptoms including “myocarditis,” “pericarditis,” “myopericarditis,” or “chest pain,” with the requirement that laboratory data were available with the individual’s troponin levels. In total, 257 reports fitting the criteria were gathered, 25 of which were regarding females, and all but one had received the Pfizer-BioNTech vaccine.
Following the second dose of the vaccine, the group found a 162.2 per million incidence rate of cardiac adverse events in boys aged 12-15, around three times higher than estimated by the CDC. In boys aged 16-17, the group also found a higher rate than estimated by the CDC by around 40%, 94 individuals per million vaccinations. The rate of adverse events was also higher than estimated by the CDC amongst girls, 13 and 13.4 per million in those aged 12-15 or 16-17, respectively.
In individuals having received only one dose of the vaccine, adverse event rates were much lower in all groups, 12 and 8.2 per million in boys aged 12-15 and 16-17, respectively. The rate was similarly reduced in girls, with no risk of adverse events in those aged 12-15 and only 2 per million in 16-17-year-olds. The group found that 15% of adverse events occurred following the first dose of the vaccine, with the majority after the second. Most adverse events occurred two days after vaccination, with 91.5% occurring within five days.
When COVID-19 hospitalization numbers are adjusted for those that attended hospital for another purpose and were incidentally infected with COVID-19, estimated to be around 40% of cases, the risk of hospitalization for COVID-19 drops notably in otherwise healthy individuals to around a 7.1, 26.7, and 37.3 per million during times of low, medium, or high transmission, respectively. In this case, however, as those with comorbidities are more likely to be hospitalized by COVID-19, the risk of vaccine-induced injury is lower than that of hospitalization in times of high transmission for 12-15-year-old boys and both moderate and high periods of disease transmission amongst 16-17-year-olds.
The long-term health effect of the mRNA vaccines on teenage boys is unknown. Few clinical trials have been conducted due to the early observation of adverse events. The group suggests that vaccination of this age group could be done on a case-by-case basis, allowing the risks and benefits to be weighed for each individual. Countries such as Germany and Norway have avoided recommending vaccinating children altogether; while the UK is considering distributing just one dose of the vaccine to these individuals, the vast majority of serious adverse events occurring after the second dose.