Establishing the rate of post-vaccination cardiac myocarditis in the 12-15 and 16-17-year-old population in the context of their COVID-19 hospitalization risk is critical for developing a vaccination recommendation framework that balances harms with benefits for this patient demographic.
Researchers have used VAERS ( Vaccine Adverse Event Reporting System ) database for reviewing retrospectively reports filed between January 1, 2021, and June 18, 2021, among adolescents ages 12-17 who received mRNA vaccination against COVID-19.
Symptom search criteria included the words chest pain, myocarditis, pericarditis and myopericarditis to identify children with evidence of cardiac injury.
The word troponin was a required element in the laboratory findings.
Inclusion criteria were aligned with the CDC working case definition for probable myocarditis.
Stratified cardiac adverse event ( CAE ) rates were reported for age, sex and vaccination dose number.
A harm-benefit analysis was conducted using existing literature on COVID-19-related hospitalization risks in this demographic.
The main outcome measures were: 1) stratified rates of mRNA vaccine-related myocarditis in adolescents age 12-15 and 16-17; and 2) harm-benefit analysis of vaccine-related CAEs in relation to COVID-19 hospitalization risk.
A total of 257 cardiac adverse events were identified. Rates per million following dose 2 among males were 162.2 ( ages 12-15 ) and 94.0 ( ages 16-17 ); among females, rates were 13.0 and 13.4 per million, respectively.
For boys 12-15 without medical comorbidities receiving their second mRNA vaccination dose, the rate of cardiac adverse event was 3.7 to 6.1 times higher than their 120-day COVID-19 hospitalization risk as of August 21, 2021 ( 7-day hospitalizations 1.5/100k population ) and 2.6-4.3-fold higher at times of high weekly hospitalization risk ( 7-day hospitalizations 2.1/100k ), such as during January 2021.
For boys 16-17 without medical comorbidities, the rate of cardiac adverse event was currently 2.1 to 3.5 times higher than their 120-day COVID-19 hospitalization risk, and 1.5 to 2.5 times higher at times of high weekly COVID-19 hospitalization.
In conclusion, post-vaccination cardiac adverse event rate was highest in young boys aged 12-15 following dose two.
For boys 12-17 without medical comorbidities, the likelihood of post vaccination dose two cardiac adverse event was 162.2 and 94.0/million respectively. This incidence exceeds their expected 120-day COVID-19 hospitalization rate at both moderate ( August 21, 2021 rates ) and high COVID-19 hospitalization incidence.
Further research into the severity and long-term sequelae of post-vaccination cardiac adverse events is warranted.
Quantification of the benefits of the second vaccination dose and vaccination in addition to natural immunity in this demographic may be indicated to minimize harm. ( Xagena )
Source: Beth Høeg T et al, Medrxiv, 2021