Echocardiographic function evaluation in adolescents following BNT162b2 Pfizer-BioNTech mRNA vaccination: A preliminary prospective study

Abstract

Background: Vaccination against coronavirus disease 2019 (COVID-19) is crucial for preventing and minimizing illness. Myocarditis and pericarditis after messenger RNA (mRNA) COVID-19 vaccination in adolescents and young adult males have been reported. Most of the studies in this area rely on retrospective symptom reporting, especially for adolescents experiencing myocarditis as a potential side effect. However, prospective postvaccination echocardiographic evaluation is rare. Methods: The study enrolled adolescents aged 12 to 15 years who received the second dose of the BNT162b2 Pfizer-BioNTech mRNA (BNT) vaccine. Serial echocardiographic examinations were conducted at baseline before vaccination, followed by subsequent assessments on days 2, 7, 14, and 28 to identify any notable differences or abnormal changes in cardiac function. Clinical symptom assessments were also recorded during each follow-up. Results: The study included 25 adolescents, comprising 14 males and 11 females, who completed the four follow-ups. Their mean age was 14 ± 1 years. The average interval between the first and second BNT vaccine doses was 90 ± 7 days. Ejection fraction values were 73.8% ± 5.2% at baseline, followed by 75.7% ± 5.3%, 75.5% ± 4.6%, 75.7% ± 4.5%, and 77.8% ± 5.8% at day 2, 7, 14, and 28, respectively. The cardiac function remained stable across all time points, with no significant differences observed between male and female participants. Within postvaccination 48 hours, 18 (72%) of the enrolled adolescents experienced temporary discomfort symptoms, which completely resolved by the final follow-up on the 28th day after vaccination. Conclusion: Although adolescents vaccinated with the second dose of BNT vaccine commonly experienced transient postvaccination discomfort, the serial echocardiographic examinations did not reveal any significant deterioration of cardiac function within 28 days. Further studies are required to investigate the incidence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) mRNA vaccination-associated myocarditis in adolescents and the related mechanisms.