The aim of the study is to prospectively evaluate the incidence of myocardial injury after the administration of the fourth dose BNT162b2 mRNA vaccine (Pfizer-BioNTech) against COVID-19.

Population-based retrospective studies suggest an association between BNT162b2 (Pfizer-BioNTech) vaccination against coronavirus disease 2019 (COVID-19) and myocarditis. While the overall incidence of myocarditis is estimated to be 2.13 per 100,000 persons, the incidence of myocardial injury and subclinical myocarditis may be higher. Adult health care workers who received the BNT162b2 vaccine in two Israeli hospitals (SZMC and Shamir) during the fourth dose campaign had blood samples taken for high-sensitivity cardiac troponin (hs-cTn) measurement at the time of vaccine administration and after 2-4 days. Post-vaccine myocardial injury was defined as hs-cTn elevation above the 99th percentile upper reference limit and >50% increase from the first measurement. Participants with evidence of myocardial injury underwent assessment for possible myocarditis including electrocardiogram and echocardiography.

Inclusion Criteria:

• Adult health care workers (≥18 years old)

Exclusion Criteria:

• Acute coronary syndrome, peri/myocarditis, cardiac catheterization, cardiac surgery, cardiac ablation, or any other invasive cardiac procedure within 14 days prior to study enrollment.
• Chronic renal failure (creatinine clearance ≤30 mL/min), or dilated or hypertrophic cardiomyopathy

Adult health care workers who received the BNT162b2 vaccine (Pfizer-BioNTech) during the fourth dose campaign