Skip to main content
2025 ISPE Annual Meeting Main banner

Vaccines

Spotlight Poster Session C

(SLC-055) Clinical course and outcomes of myocarditis/pericarditis cases following mRNA-1273 vaccination compared to cases not following COVID-19 vaccination: interim analysis of a VAC4EU cohort study

Tuesday, August 26, 2025
12:15 PM - 1:15 PM ET

    Presenting Author(s)

  • Laura Zwiers, MPhil

    Scientific Officer
    Julius Clinical, Netherlands

    • Co-Author(s)

  • Fv

    Frank van der Velden

    Julius Clinical, Netherlands

  • SS

    Samantha St Laurent

    Moderna
    Cambridge, Massachusetts, United States

  • Daina B. Esposito, MPH, PhD

    Executive Director, Global Safety Epidemiology
    Moderna
    Cambridge, Massachusetts, United States

  • Lei Zhu

    Moderna, United States

  • VU

    Veronica Urdaneta

    Moderna, United States

  • ME

    Magalie Emilebacker, PharmD, CCRP

    Director, Pharmacovigilance Sciences
    Moderna
    Alexandria, Virginia, United States

  • DW

    Daniel Weibel

    Vaccine monitoring collaboration for Europe (VAC4EU), Brussels, Belgium, Netherlands

  • AL

    Angela Lupattelli

    Professor
    Pharmacoepidemiology and Drug Safety Research Group, Department of Pharmacy, Faculty of Mathematics and Natural Sciences, University of Oslo, Norway

  • AD

    Anteneh Desalegn

    Pharmacoepidemiology and Drug Safety Research Group, Department of Pharmacy, Faculty of Mathematics and Natural Sciences, University of Oslo, Norway

  • MZ

    Mahmoud Zidan

    Researcher
    Pharmacoepidemiology and Drug Safety Research Group, Department of Pharmacy, Faculty of Mathematics and Natural Sciences, University of Oslo
    Oslo, Norway

  • Vera Ehrenstein, MPH, DSc

    Professor
    Department of Clinical Epidemiology and Center for Population Medicine, Aarhus University, Aarhus, Denmark
    Aarhus, Midtjylland, Denmark

  • JW

    Jannik Wheler

    Department of Clinical Epidemiology and Center for Population Medicine, Aarhus University, Aarhus Denmark, Denmark

  • Felipe Villalobos

    Primary care researcher
    Fundació Institut Universitari per a la recerca a l'Atenció Primària de Salut Jordi Gol i Gurina (IDIAPJGol), Barcelona, Spain, Spain

  • CB

    Carlo Alberto Bissacco

    Fundació Institut Universitari per a la recerca a l'Atenció Primària de Salut Jordi Gol i Gurina (IDIAPJGol), Barcelona, Spain, Spain

  • DM

    Denise Morris

    Drug Safety Research Unit, Southampton, UK, United Kingdom

  • CF

    Catherine Fry

    Drug Safety Research Unit, Southampton, UK, United Kingdom

  • AU

    Arantxa Urchueguía

    Vaccine Research Department, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO-Public Health), Valencia, Spain, Spain

  • MH

    María Herrero-Silvestre

    Vaccine Research Department, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO - Public Health)
    Valencia, Comunidad Valenciana, Spain

  • MJ

    Marjolein Jansen

    Julius Clinical, Netherlands

  • DG

    Diederick Grobbee, MD, PhD

    Julius Clinical, Netherlands

  • DO

    David S.Y. Ong, MD, PhD, PharmD

    Julius Clinical, Netherlands

Background: Myocarditis and pericarditis are recognized as possible rare adverse events that may occur following COVID-19 mRNA vaccines, including mRNA-1273.

Objectives: The aim was to characterize the clinical course of myo- and pericarditis of varying origin, including cases associated with mRNA-1273 vaccination and cases not associated with COVID-19 vaccination and to identify risk factors for severe outcomes (cardiac or thromboembolic complications, severe hospital outcomes, all-cause hospital readmission, and death).

Methods: This cohort study utilized secondary health data from the VAC4EU network through five data experts and access partners across four European countries (national registries in Denmark and Norway, VID (Valencia region) and SIDIAP (Catalonia region) in Spain and CPRD Aurum in the UK). It included individuals diagnosed with myo- or pericarditis within 30 days after mRNA-1273 vaccination (exposed) and those that did not receive any COVID-19 vaccine in the 30 days before myo- or pericarditis onset (unexposed), and were enrolled in the database for at least a year. Different follow-up windows at 1, 3, 6 and 12 months after myo- or pericarditis onset were considered in the analysis. Cox regression analyses were used to estimate hazards ratios (HRs) for sequelae.

Results: The number of myo- and/or pericarditis cases in each database varied from 2,700 to 6,908, of which 90 to 158 were associated with mRNA-1273. Exposed cases had lower prevalence of pre-existing comorbidities and shorter hospital stays than unexposed cases. Two percent (2%) of the exposed myocarditis cases compared to 5% of unexposed cases were severe. None of the post-mRNA-1273 pericarditis cases were severe. Cox regression models of the combined exposed and unexposed cases showed that age (HR range: 1.00-1.03), Charlson Comorbidity Index (CCI) score (HR range: 1.18-2.41), and history of cardiac drug use (HR range 1.24-4.00) were risk factors for cardiac complications in both myo- and pericarditis cases across follow-up windows. CCI score (HR range: 1.09-2.11) and previous healthcare use (HR range: 1.13-6.89) were risk factors for severe hospital outcomes and hospital readmission in both myo- and pericarditis cases. Age (HR range: 1.04-1.11) and CCI score (HR range: 1.30-2.32) were the most apparent risk factors for death in both myo- and pericarditis cases.

Conclusions: Post-mRNA-1273 myocarditis cases were less severe and had fewer pre-existing comorbidities compared to unexposed cases. Risk factors for cardiac complications, severe hospital outcomes, and mortality after myo- or pericarditis diagnosis include older age, higher CCI score, and previous healthcare use.