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Abstract
Objective To investigate the clinical outcomes of myocarditis associated with mRNA vaccines against the SARS-CoV-2 virus compared with other types of myocarditis.
Design Population based cohort study.
Setting Nationwide register data from four Nordic countries (Denmark, Finland, Norway, and Sweden), from 1 January 2018 to the latest date of follow-up in 2022.
Participants The Nordic myocarditis cohort; 7292 individuals aged ≥12 years who had an incident diagnosis of myocarditis as a main or secondary diagnosis, in a population of 23 million individuals in Denmark, Finland, Norway, and Sweden.
Main outcome measures Heart failure, or death from any cause within 90 days of admission to hospital for new onset myocarditis, and hospital readmission within 90 days of discharge to hospital for new onset myocarditis. Clinical outcomes of myocarditis associated with SARS-CoV-2 mRNA vaccination, covid-19 disease, and conventional myocarditis were compared.
Results In 2018-22, 7292 patients were admitted to hospital with new onset myocarditis, with 530 (7.3%) categorised as having myocarditis associated with SARS-CoV-2 mRNA vaccination, 109 (1.5%) with myocarditis associated with covid-19 disease, and 6653 (91.2%) with conventional myocarditis. At the 90 day follow-up, 62, nine, and 988 patients had been readmitted to hospital in each group (vaccination, covid-19, and conventional myocarditis groups, respectively), corresponding to a relative risk of readmission of 0.79 (95% confidence interval 0.62 to 1.00) and 0.55 (0.30 to 1.04) for the vaccination type and covid-19 type myocarditis groups, respectively, compared with the conventional myocarditis group. At the 90 day follow-up, 27, 18, and 616 patients had a diagnosis of heart failure or died in the vaccination type, covid-19 type, and conventional myocarditis groups, respectively. The relative risk of heart failure within 90 days was 0.56 (95% confidence interval 0.37 to 0.85) and 1.48 (0.86 to 2.54) for myocarditis associated with vaccination and covid-19 disease, respectively, compared with conventional myocarditis; the relative risk of death was 0.48 (0.21 to 1.09) and 2.35 (1.06 to 5.19), respectively. Among patients aged 12-39 years with no predisposing comorbidities, the relative risk of heart failure or death was markedly higher for myocarditis associated with covid-19 disease than for myocarditis associated with vaccination (relative risk 5.78, 1.84 to 18.20).
Conclusions Compared with myocarditis associated with covid-19 disease and conventional myocarditis, myocarditis after vaccination with SARS-CoV-2 mRNA vaccines was associated with better clinical outcomes within 90 days of admission to hospital.
- COVID-19
- Epidemiology
- Heart failure
Data availability statement
Data may be obtained from a third party and are not publicly available. Individual level data underlying the country specific analyses were only available within each Nordic country. The data do not belong to the authors and they are not permitted to share these data, except as presented in this manuscript.
This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
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Data availability statement
Data may be obtained from a third party and are not publicly available. Individual level data underlying the country specific analyses were only available within each Nordic country. The data do not belong to the authors and they are not permitted to share these data, except as presented in this manuscript.
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Footnotes
Twitter @anders_hviid
Contributors AHu, HLG, PH, OK, RL, and AHu contributed to the concept and design of the study; AHu, HLG, PH, JVH, NP, NG, TH, JD, OK, and RL, contributed to the acquisition and analysis of the data; JVH, NP, NG, TH, and OK performed the statistical analysis; all authors contributed to critical revision of the manuscript for important intellectual content. The guarantor (AHu) accepts full responsibility for the finished work and the conduct of the study, had access to the data, and controlled the decision to publish. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted. Transparency: The lead author (the guarantor) affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.
Funding AHu is supported by a postdoctoral research grant from the Lundbeck Foundation (grant No R322-2019-2800). The funder had no role in considering the study design or in the collection, analysis, interpretation of data, writing of the report, or decision to submit the article for publication.
Competing interests All authors have completed the ICMJE uniform disclosure form at www.icmje.org/disclosure-of-interest/ and declare: no support from any organisation for the submitted work; AHu is supported by a postdoctoral research grant from the Lundbeck Foundation (grant No R322-2019-2800); AHv reports being a Scientific Advisory Board member for VAC4EU; LK reports speaker’s fees from Novo Nordisk, Novartis, AstraZeneca, Bayer, and Boehring, outside of the submitted work; PH reports being a member of an expert group, Future Rheumatology Advisory Board (2016 and 2017), funded by Pfizer; the Finnish Institute for Health and Welfare has a strategic policy of public private partnership, but none of the researchers of this report was involved with industry sponsored studies; OK reports participation in research projects funded by Novo Nordisk and LEO Pharma, all regulator mandated phase IV studies, all with funds paid to his institution (no personal fees), outside of the submitted work; HLG reports previous participation in research projects and clinical trials funded by Novo Nordisk, GSK, AstraZeneca, and Boheringer-Ingelheim, all related to diabetes and paid to her previous institution, Oslo University Hospital (no personal fees); HLG has received lecture fees and participated in advisory boards from several pharmaceutical companies before 2019 related to diabetes and metabolism; RL reports participation in a research project funded by Sanofi-Aventis, a regulator mandated phase IV study, with funds paid to his institution (no personal fees) (2011), outside of the submitted work; RL has received a lecture fee from Pfizer (2016), outside of the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
Provenance and peer review Not commissioned; externally peer reviewed.
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