Cardiovascular safety signals in Israeli adolescents following COVID-19 Vaccination: Evidence from an unprocessed FOIA dataset

Background: During the first year of the COVID-19 vaccination campaign, vaccine-associated cardiac risk was largely portrayed as rare, mild, and transient. However, according to the State Comptroller of Israel – a country often regarded as the world’s vaccination laboratory – most adverse event reports submitted during the campaign by Clalit Health Services, Israel’s largest health provider, were not processed. This study discloses and analyzes the majority of these previously unexamined reports, obtained through Freedom of Information Act (FOIA) requests.

Methods and Findings: A large anonymized dataset comprising 294,877 mild and severe adverse event reports (e.g., seizures, Guillain–Barré syndrome), documented by healthcare personnel between December 2020 and December 2024, and was made publicly available on the Open Science Framework. Using a deliberately conservative analytical strategy, 277 unique cardiovascular events were identified among underage vaccinees, including acute cardiovascular injury, myocarditis, and pericarditis. Events were broadly distributed across genders (145 girls) and timeframes (133 after the first dose, 84 within 21 days of the second dose, and 60 more than 21 days after the second dose). Notably, 271 of these cases (98%) occurred among adolescents aged 12–16 within a narrow six-week window, temporally coinciding with the expansion of vaccine eligibility to this age group.

Conclusions: The findings indicate a substantial and previously unrecognized cardiovascular safety signal. Even under deliberately conservative assumptions, the observed age- and time-specific clustering reflects a magnitude well beyond background expectations. Earlier disclosure and analysis of these data could have enabled age-sensitive risk–benefit assessments and more adaptive vaccination policies.