Key result
The incidence rate ratio for inflammatory heart diseases did not significantly differ between the 2021 COVID-19 pandemic period (IRR 0.74) and the 2019 pre-pandemic period (IRR 0.67; P=0.45).
Why the study?
Heterogeneous diagnostic criteria for postvaccination inflammatory heart diseases may overestimate incidence rates, prompting evaluation of the impact of COVID-19 vaccines on myocarditis and pericarditis incidence.
Does the COVID-19 vaccination period increase the incidence of acute myocarditis and pericarditis compared to the pre-pandemic period?
Observational
Yes
Does the COVID-19 vaccination period increase the incidence of acute myocarditis and pericarditis compared to the pre-pandemic period?
Absolute Event Rate: 0.74% vs 0.67%
p-value: p=0.45
The incidence of acute myocarditis and pericarditis did not significantly increase during the COVID-19 vaccination period compared to the pre-pandemic period, supporting the cardiovascular safety of the vaccines.
No increase in myocarditis/pericarditis incidence in 2021 vs 2019; supports safety monitoring yet leaves causal links hypothesis-generating.
AIMS: Some studies about myocarditis and pericarditis following COVID-19 vaccination raised concerns worldwide. However, the heterogeneous diagnostic criteria for postvaccination inflammatory heart diseases may result in overestimating incidence rates. The aim of this multicentre Italian registry is to evaluate the impact of COVID-19 vaccines on the incidence of myocarditis and pericarditis in the Italian population. METHODS: Consecutive patients admitted to Italian hospitals for endomyocardial and/or cardiac magnetic resonance proven acute myocarditis and/or pericarditis in the same period (1 June-31 October) of 2019 and 2021 were enrolled, irrespective of the potential association with the COVID-19 vaccines. Acute pericarditis and/or myocarditis were defined as 'vaccine-related' if clinical presentation occurred within 15 days after COVID-19 vaccination, independently of the dose. RESULTS: There was a comparable incidence rate ratio (IRR) for inflammatory heart diseases in 2019 and 2021 (2019: IRR 0.67 versus 2021: IRR 0.74, P = 0.45). In particular, the IRR did not differ in myocardial involvement (2019: IRR 0.33 versus 2021: IRR 0.33, P = 1) and pericarditis (2019: IRR 0.37 versus 2021: IRR 0.49, P = 0.09) in both periods. Among 125 cases registered in 2021, 32 (25.6%) were 'vaccine-related'. Among those who experienced 'vaccine-related' myocarditis and/or pericarditis, men with age under 40 years were over-represented (53.12%, P = 0.021). CONCLUSION: In a nationwide Italian survey comparing pandemic with prepandemic periods, the overall data do not indicate significant concerns about an increased incidence of pericarditis and myocarditis, suggesting that the vaccine is generally well tolerated for these specific conditions.
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Birtolo et al. (2025) conducted an observational in Acute myocarditis and/or pericarditis. COVID-19 pandemic period (2021) vs. Pre-pandemic period (2019) was evaluated on Incidence rate ratio (IRR) for inflammatory heart diseases (p=0.45). The incidence rate ratio for inflammatory heart diseases did not significantly differ between the 2021 COVID-19 pandemic period (IRR 0.74) and the 2019 pre-pandemic period (IRR 0.67; P=0.45).
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