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This research has not been peer-reviewed. It is a preliminary report that should not be regarded as conclusive, guide clinical practice or health-related behaviour, or be reported in news media as established information.

Objectives 

To determine whether spontaneous reporting rates of myocarditis and pericarditis differed in immunocompromised patients compared to the whole population overall, and in terms of demographics, vaccine dose, and time-to-onset.

Design 

Systematic review of spontaneously reported data from the European Union/European Economic Area (EU/EEA) and the United States (US).

Data Sources 

EudraVigilance (EU/EEA) and Vaccine Adverse Event Reporting System (VAERS; US) spontaneous reporting databases were searched from date of vaccine launch to 30 November 2021.

Eligibility criteria 

Publicly available spontaneous reporting data for “Myocarditis” and “Pericarditis” from EU/EEA and US following COVID-19 mRNA vaccines. Reports with comorbidities or concurrent medication indicative of transplantation, HIV infection, or cancer (“immunocompromised” population) were compared with each overall database population.

Data extraction and synthesis 

Two researchers extracted data. Spontaneously reported events of myocarditis and pericarditis were presented for immunocompromised populations for each data source, stratified by age, sex, dose, and time-to-onset (where available). Seriousness of each event was determined according to the ICH E2A definition. Proportional Reporting Ratio (PRR) was calculated.

Results 

There were 106 reports of myocarditis and pericarditis amongst immunocompromised individuals overall. Seriousness was comparable between the immunocompromised and overall populations in both databases. No trends in age or sex were observed amongst immunocompromised individuals. Most reports (54.4%) to VAERS followed a second vaccine dose and 70.2% of events occurred within 14 days. The frequency of reporting was similar to the wider population (PRR=1.36 [95% CI= 0.89-1.82] for VAERS population).

Conclusions 

Myocarditis and pericarditis following COVID-19 vaccination are very rare, and benefits of COVID-19 vaccination continue to outweigh any perceived risks. Reporting rates of myocarditis and pericarditis were similar in immunocompromised individuals, however defining characteristics differed compared to the whole population; therefore, continued monitoring of adverse events following vaccination remains vital to understand differences between population subgroups.