Acute Appendicitis After COVID-19 Vaccines in Italy: A Self-Controlled Case Series Study

Cases of appendicitis were identified in the pivotal randomized clinical trial on BNT162b2 mRNA vaccine and reported from coronavirus disease 2019 (COVID-19) vaccine pharmacovigilance systems. Three cohort studies and two self-controlled case series (SCCS) studies evaluating the association between mRNA vaccines and appendicitis reported discordant results. To address this uncertainty, the present study examines in a large population, with a SCCS design, the association between mRNA (BNT162b2 and mRNA-1273) and, for the first time, viral vector (ChAdOx1-S and Ad26.COV2-S) COVID-19 vaccines and acute appendicitis.