Severe Myocarditis Increase in Children Associated With Parvovirus B19 Infection

BACKGROUND: Following a surge in myocarditis in Germany since August 2023, many with parvovirus B19 (B19V) detection, concerns arose about causes and countermeasures. OBJECTIVES: The authors aimed to verify the association among B19V, myocarditis increase, and severity. METHODS: Data from the pediatric multicenter registry (MYKKE) from 27 centers were analyzed. B19V myocarditis cases were defined by polymerase chain reaction (PCR) positivity in blood or myocardium with clinical or histopathologic myocarditis evidence. Comprehensive clinical, histopathologic, and epidemiologic analyses were conducted. Past patients were hospitalized from 2013 to July 2023, current from August 2023 to November 2024. Registry data were compared with surveillance and consultant laboratory data. Specimens of current cases underwent metagenomic analysis and B19V sequencing. RESULTS: Since 2013, 922 myocarditis patients including 126 (13.6%) with B19V myocarditis were enrolled. With 57 of 126 (45.2%) current cases, B19V myocarditis increased, compared with other myocarditis causes. Most current cases were patients who were