Myocarditis and pericarditis after immunization: Gaining insights through the Vaccine Adverse Event Reporting System.

Abstract Aim To characterize cases of myocarditis (MC) and pericarditis (PC) recorded in the Vaccine Adverse Event Reporting System (VAERS). Methods Cases were extracted from VAERS (2011–2015) and assessed for causality using standardized WHO algorithm. Disproportionality analysis was performed through reporting odds ratio (ROR) with 95%CI. MEDLINE was also searched. Results In VAERS, 199 cases of MC or PC were collected, among which 149 reported smallpox vaccine. The remaining were: 15 cases in 'YOUNGER GROUP' (YG; <18 years old) and 35 in 'OLDER GROUP' (OG; >18 years old). Main reported vaccines were against Human Papilloma Virus (n = 6) in YG and influenza (n = 16) in OG. Causality always resulted "undeterminate" for YG, whereas either "undetermined" (30 cases) and "correlated" (3 cases) for OG. Statistically significant ROR was found in YG for meningococcal vaccine (ROR = 3.55; 95%CI = 1.23–10.24) and in OG for thyphoid vaccine (11.13; 7.73–16.03), Japanese encephalitis vaccine (8.54; 2.7–27.01), anthrax (25.5; 18.8–34.5), and, as expected, smallpox (71.88; 49.25–104.89). In MEDLINE, 91 articles were found: positive/possible causality was frequently reported. Conclusions MC and PC after immunization appear extremely rare; only in very few cases can a role of vaccine be actually identified. Signals for vaccines against typhus, Japanese encephalitis, anthrax and meningococcus warrant monitoring. Highlights • For both literature and VAERS, myo/pericarditis after immunization are extremely rare. • Cases frequently present abnormalities in ECG and in myocardial necrosis markers. • Chest pain in a recently immunized young is useful for differential diagnosis. [ABSTRACT FROM AUTHOR]