SARS-CoV-2 vaccination and myocarditis or myopericarditis: population based cohort study

Abstract

Objective To investigate the association between SARS-CoV-2 vaccination and myocarditis or myopericarditis. Design Population based cohort study. Setting Denmark. Participants 4 931 775 individuals aged 12 years or older, followed from 1 October 2020 to 5 October 2021. Main outcome measures The primary outcome, myocarditis or myopericarditis, was defined as a combination of a hospital diagnosis of myocarditis or pericarditis, increased troponin levels, and a hospital stay lasting more than 24 hours. Follow-up time before vaccination was compared with follow-up time 0-28 days from the day of vaccination for both first and second doses, using Cox proportional hazards regression with age as an underlying timescale to estimate hazard ratios adjusted for sex, comorbidities, and other potential confounders. Results During follow-up, 269 participants developed myocarditis or myopericarditis, of whom 108 (40%) were 12-39 years old and 196 (73%) were male. Of 3 482 295 individuals vaccinated with BNT162b2 (Pfizer-BioNTech), 48 developed myocarditis or myopericarditis within 28 days from the vaccination date compared with unvaccinated individuals (adjusted hazard ratio 1.34 (95% confidence interval 0.90 to 2.00); absolute rate 1.4 per 100 000 vaccinated individuals within 28 days of vaccination (95% confidence interval 1.0 to 1.8)). Adjusted hazard ratios among female participants only and male participants only were 3.73 (1.82 to 7.65) and 0.82 (0.50 to 1.34), respectively, with corresponding absolute rates of 1.3 (0.8 to 1.9) and 1.5 (1.0 to 2.2) per 100 000 vaccinated individuals within 28 days of vaccination, respectively. The adjusted hazard ratio among 12-39 year olds was 1.48 (0.74 to 2.98) and the absolute rate was 1.6 (1.0 to 2.6) per 100 000 vaccinated individuals within 28 days of vaccination. Among 498 814 individuals vaccinated with mRNA-1273 (Moderna), 21 developed myocarditis or myopericarditis within 28 days from vaccination date (adjusted hazard ratio 3.92 (2.30 to 6.68); absolute rate 4.2 per 100 000 vaccinated individuals within 28 days of vaccination (2.6 to 6.4)). Adjusted hazard ratios among women only and men only were 6.33 (2.11 to 18.96) and 3.22 (1.75 to 5.93), respectively, with corresponding absolute rates of 2.0 (0.7 to 4.8) and 6.3 (3.6 to 10.2) per 100 000 vaccinated individuals within 28 days of vaccination, respectively. The adjusted hazard ratio among 12-39 year olds was 5.24 (2.47 to 11.12) and the absolute rate was 5.7 (3.3 to 9.3) per 100 000 vaccinated individuals within 28 days of vaccination. Conclusions Vaccination with mRNA-1273 was associated with a significantly increased risk of myocarditis or myopericarditis in the Danish population, primarily driven by an increased risk among individuals aged 12-39 years, while BNT162b2 vaccination was only associated with a significantly increased risk among women. However, the absolute rate of myocarditis or myopericarditis after SARS-CoV-2 mRNA vaccination was low, even in younger age groups. The benefits of SARS-CoV-2 mRNA vaccination should be taken into account when interpreting these findings. Larger multinational studies are needed to further investigate the risks of myocarditis or myopericarditis after vaccination within smaller subgroups.

Personalized Management of Myocarditis and Inflammatory Cardiomyopathy in Clinical Practice

“…The authors concluded that vaccination with mRNA-1273 was associated with a significantly increased risk of myocarditis or myopericarditis in the Danish population. However, the overall risks are low and must be balanced against the individual and societal benefits associated with vaccination [23].…”

The Safety of Anti-SARS-CoV-2 Vaccines: Vigilance Is Still Required

“…Myocarditis observed in the days following the injection of messenger RNA vaccine in young individuals is another well-established rare complication, first identified within the Israeli health system [ 5 ]. The higher risk with the mRNA-1273 (Moderna) vaccine as compared to the BNT162b2 (Pfizer/BioNTech) vaccine [ 6 ] led several countries to only use the BNT162b2 vaccine in younger individuals and to cut the dose of the mRNA-1273 vaccine by half when given as a booster.…”

Folic acid supplementation and the complexities of blame

“…What if you wrongly advise millions of people, on national television, about the efficacy of vaccines (https://www.sciencemediacentre.org/expert-reaction-to-a-doctor-challenging-the-health-secretary-sajid-javid-on-compulsory-vaccination-at-kings-college-hospital)?4 Or fail to stay up to date with the latest research on vaccines and myocarditis (doi:10.1136/bmj-2021-068665)?5 Perhaps you need an update on management of chronic anal fissures (doi:10.1136/bmj-2021-066834) and extreme preterm birth (doi:10.1136/bmj-2021-055924)?67 How about the company executives refusing scrutiny of their trial data while profiting by the billion (doi:10.1136/bmj.o102)?8 Or the editors, journalists, and politicians unwilling to cover the growing concern about China’s human rights abuses (doi:10.1136/bmj.o44)?9 What of Facebook’s responsibility in trying to censor legitimate concerns about the conduct of clinical trials (doi:10.1136/bmj.o95)?10…”