Hospitalisations with myocarditis before and during the COVID-19 pandemic – a nationwide cohort study

Q: What are the key findings of this study?

The COVID-19 pandemic was associated with a significantly steeper quarterly increase in myocarditis hospitalizations (slope 2.008) compared to the pre-pandemic period (slope 1.141).

Q: What is the clinical evidence from this study?

Study design: Cohort. Population: Myocarditis (n=7053). Intervention: COVID-19 pandemic vs. Pre-pandemic period (2012-2019). Primary outcome: Trends in hospitalizations with myocarditis (quarterly slope of incidence) (slope 2.008, 95% CI 2.006 to 2.011, p=<0.001).

Q: What does this research mean for the field?

Hospitalizations for myocarditis increased significantly during the COVID-19 pandemic compared to pre-pandemic trends, with the steepest rise observed in young and middle-aged males. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Q: What question did this study set out to answer?

To assess nationwide trends in hospitalisations with myocarditis before and during the COVID-19 pandemic in Switzerland.

Jérémie Héritier; Rahel Laager; Andreas Schelldorfer; Claudia Gregoriano; Beat Müeller; Philipp Schüetz; Alexander Kutz

doi:10.57187/4794

September 24, 2026Swiss Medical WeeklyOpen Access

Hospitalisations with myocarditis before and during the COVID-19 pandemic – a nationwide cohort study

View Full Paper

Ask AI

Bookmark

Share

Key result

COVID-19 pandemic linked to a ~76% steeper quarterly increase in myocarditis hospitalizations vs pre-pandemic.

slope 2.008
95% CI 2.006 to 2.011
P<0.001
n=7,053

Why the study?

Does the COVID-19 pandemic period increase the incidence of hospitalizations with myocarditis compared to the pre-pandemic period?

Key Points

To assess nationwide trends in hospitalisations with myocarditis before and during the COVID-19 pandemic in Switzerland.
Nationwide cohort study analyzing 7,053 hospitalisations with myocarditis across pre-pandemic (2012–2019, n = 4,304) and pandemic (2020–2022, n = 2,749) periods.
Trends were evaluated using linear mixed-effects segmented regression models and stratified by sex and age.
Secondary endpoints evaluated included in-hospital mortality, intensive care unit admission, length of stay, and 30-day hospital readmission.
Incidence increased from 26.7 cases per 100,000 hospitalisations in 2012 to 73.8 per 100,000 in 2022 (p for trend <0.001).
The quarterly incidence slope rose from 1.141 (95% CI: 1.140 to 1.141) pre-pandemic to 2.008 (95% CI: 2.006 to 2.011) during the pandemic, with the steepest increases occurring in young and middle-aged males.
Population-adjusted sensitivity analyses showed an increase from 1.0 to 2.6 hospitalisations per 100,000 inhabitants between 2012 and 2022 (p for trend <0.001), with quarterly slopes rising from 0.041 (95% CI: 0.041 to 0.041) to 0.060 (95% CI: 0.060 to 0.060; p <0.001).

Study Design

Type

Cohort (n=7,053)

Multicenter

Yes

Structured PICO

Does the COVID-19 pandemic period increase the incidence of hospitalizations with myocarditis compared to the pre-pandemic period?

P

Population

7,053 hospitalizations with myocarditis in Switzerland, comparing incidence and outcomes between the pre-pandemic (2012-2019) and COVID-19 pandemic (2020-2022) periods.

E

Exposure

The COVID-19 pandemic period (years 2020-2022)

C

Comparator

The pre-pandemic period (years 2012-2019)

O

Outcome

Difference in incidence rates of hospitalization with myocarditis between the pre-pandemic period (2012-2019) and the pandemic period (2020-2022)hard clinical

Main Result

Effect estimate: slope 2.008 (95% CI 2.006 to 2.011)

Absolute Event Rate: 2.008% vs 1.141%

p-value: p=<0.001

The COVID-19 pandemic was associated with a marked acceleration in the incidence of myocarditis hospitalizations, particularly among young and middle-aged males, alongside worse in-hospital outcomes.

Limitations

Use of administrative data does not allow for the confirmation of diagnostic methods or the determination of myocarditis etiology.
Could not assess whether cases were directly related to SARS-CoV-2 infection, vaccination, or other causes.
Database includes only hospitalization diagnoses and lacks outpatient history or medication data.
Relied on Swiss nationwide data and may not be fully generalizable to countries with different demographics or healthcare access.
Greater use of cardiac MRI over time may have increased the detection of myocarditis, potentially reflecting improved ascertainment rather than a true increase in disease burden.
Potential misclassification and underreporting of diagnoses and diagnostic procedures cannot be ruled out.
Use of administrative data without confirmation of diagnostic methods or etiology
Inability to assess whether cases were related to SARS-CoV-2 infection, vaccination, or other causes
Lack of outpatient history or medication data
Reliance on Swiss nationwide data which may not be fully generalizable
Greater use of cardiac MRI over time may have increased detection (ascertainment bias)
Potential misclassification and underreporting of diagnoses

Implication

Pandemic acceleration in myocarditis hospitalizations warrants surveillance; leaves open infection, vaccination, or detection contributions pending prospective studies.

Abstract

AIMS OF THE STUDY: Over the past decade, there has been a steady increase in myocarditis cases, paralleling the expanded availability and use of cardiac magnetic resonance imaging. Although some have speculated that COVID-19 or its vaccines may be contributing to this increase, recent studies have not provided conclusive proof. Therefore, this study aims to analyse the association between COVID-19 and myocarditis in hospitalised patients. METHODS: In this nationwide cohort study, the primary outcome was trends in hospitalisations with myocarditis before (years 2012-2019) and during (years 2020-2022) the COVID-19 pandemic. Trends were calculated using linear mixed-effects segmented regression models. Secondary outcomes included in-hospital mortality, intensive care unit admission, length of stay, and 30-day hospital readmission. Results were stratified by sex and age for subgroup analyses. RESULTS: During the pre-pandemic period, 4,304 hospitalisations with myocarditis were recorded, compared with 2,749 during the pandemic. The incidence rate of myocarditis increased from 26.7 cases per 100,000 hospitalisations in 2012 to 73.8 per 100,000 in 2022 (p for trend <0.001). The quarterly slope of incidence rose significantly during the pandemic (slope, 2.008 [95% CI: 2.006 to 2.011]) compared with that during the pre-pandemic period (slope, 1.141 [95% CI: 1.140 to 1.141]). Subgroup analyses showed the steepest increases in young and middle-aged males. Sensitivity analyses based on the Swiss population confirmed this pattern, with a population-adjusted quarterly increase in myocarditis hospitalisations from 1.0 to 2.6 per 100,000 inhabitants between 2012 and 2022 (p for trend <0.001). CONCLUSION: This nationwide cohort study found a marked increase in the incidence of hospitalisations with myocarditis during the COVID-19 pandemic, suggesting a causal relationship between COVID-19 infection and/or its vaccination and the increased incidence of myocarditis.

Discussion

No takes yet. Share an insight, caveat, or question.

Cite This Study

Héritier et al. (2026) conducted a cohort in Myocarditis (n=7,053). COVID-19 pandemic vs. Pre-pandemic period (2012-2019) was evaluated on Trends in hospitalizations with myocarditis (quarterly slope of incidence) (slope 2.008, 95% CI 2.006 to 2.011, p=<0.001). The COVID-19 pandemic was associated with a significantly steeper quarterly increase in myocarditis hospitalizations (slope 2.008) compared to the pre-pandemic period (slope 1.141).

synapsesocial.com/papers/6ab9b4d47822ec8fc3d8f04a https://doi.org/10.57187/4794

Topics

Myocarditis

View Full Paper

Ask AI

Bookmark

Share

Hospitalisations with myocarditis before and during the COVID-19 pandemic – a nationwide cohort study

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

Topics

Hospitalisations with myocarditis before and during the COVID-19 pandemic – a nationwide cohort study

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

Keep reading

Topics

Keep reading