November 4, 2025

Myocarditis in children after Covid infection or Covid mRNA vaccination

We know from previous research that both Covid infection and Covid mRNA vaccination are associated with the rare complication of myocarditis and pericarditis (heart inflammation) in children.

A new study aims to quantify what the size of this risk was during the study period using UK data.

The study used health records covering 98% of England’s child population between January 2020 and December 2022, to assess the short- and long-term risks of health conditions associated with Covid infection and vaccination.

The study was published in the Lancet Child & Adolescent Health. Journalists came to this briefing to hear from some of the authors of the study, and to ask their questions.

Please note that, while providing useful data, the study was based on data from during and just after the pandemic so the risk currently represented by Covid infection (given most children might have had several more infections since then) may be different.

Speakers included:

Prof Angela Wood, Joint Director of the Cambridge HDR UK Regional Network; Professor of Health Data Science, Associate Director and Theme Lead for Whole Population Data and the CVD-COVID-UK/COVID-IMPACT programme at the BHF Data Science Centre

Prof Pia Hardelid, Professor of Epidemiology, UCL Institute of Child Health, UCL

This Briefing was accompanied by an SMC Roundup of comments.