Key result
First-dose mRNA COVID-19 vaccines linked to excess myocarditis risk, peaking at ~17 per million doses.
Why the study?
This study was conducted to assess the reporting rates of myocarditis and pericarditis following the first dose of mRNA COVID-19 vaccines in Europe.
Does the first dose of mRNA COVID-19 vaccines increase the risk of myocarditis and pericarditis in Europeans?
Observational (n=557,868,504)
Does the first dose of mRNA COVID-19 vaccines increase the risk of myocarditis and pericarditis in Europeans?
Effect estimate: 17.27 per 1 million (95% CI 16.34-18.26)
This large-scale European pharmacovigilance study confirms a rare but statistically significant excess risk of myocarditis following the first dose of mRNA COVID-19 vaccines, particularly with CX-024414 (Moderna).
Alerts clinicians to monitor myocarditis post-first mRNA dose; leaves open causality and absolute risk in real-world cohorts.
This study assessed the myocarditis and pericarditis reporting rate of the first dose of mRNA COVID-19 vaccines in Europe. Myocarditis and pericarditis data pertinent to mRNA COVID-19 vaccines (1 January 2021-11 February 2022) from EudraVigilance database were combined with European Centre for Disease Prevention and Control (ECDC)'s vaccination tracker data. The reporting rate was expressed as events (occurring within 28 days of the first dose) per 1 million individuals vaccinated. An observed-to-expected (OE) analysis quantified excess risk for myocarditis or pericarditis following the first mRNA COVID-19 vaccination. The reporting rate of myocarditis per 1 million individuals vaccinated was 17.27 (95% CI, 16.34-18.26) for CX-024414 and 8.44 (95% CI, 8.18-8.70) for TOZINAMERAN; and of pericarditis, 9.76 (95% CI, 9.06-10.51) for CX-024414 and 5.79 (95% CI, 5.56-6.01) for TOZINAMERAN. Both vaccines produced a myocarditis standardized morbidity ratio (SMR) > 1, with the CX-024414 vaccine having a greater SMR than TOZINAMERAN. Regarding TOZINAMERAN, SMR for pericarditis was >1 when considering the lowest background incidence, but <1 when considering the highest background incidence. Our results suggest an excess risk of myocarditis following the first dose of the mRNA COVID-19 vaccine, but the relationship between pericarditis and the mRNA COVID-19 vaccine remains unclear.
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Tome et al. (2023) conducted an observational in Myocarditis and pericarditis (n=557,868,504). First dose of mRNA COVID-19 vaccines (CX-024414 and TOZINAMERAN) vs. Expected background incidence was evaluated on Reporting rate of myocarditis per 1 million individuals vaccinated within 28 days of the first dose of CX-024414 (17.27 per 1 million, 95% CI 16.34-18.26). The first dose of mRNA COVID-19 vaccines was associated with an excess risk of myocarditis, with a reporting rate of 17.27 per 1 million for CX-024414 and 8.44 per 1 million for TOZINAMERAN.
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