Massive England study finds myocarditis and pericarditis were rarer and shorter after immunisation than after Covid infection.
Cambridge, England, 19 January 2026 – Health misinformation remains one of Covid’s most damaging legacies, fuelling vaccine hesitancy and weakening trust in public health advice worldwide. In this climate of confusion, a major new study from England offers clear evidence on a key question: what is riskier for children’s hearts, Covid infection or vaccination?
Researchers analysing anonymised health records of almost 14 million children and young people under 18 (around 85% of England’s youth population) found that Covid infection carried a substantially higher risk of rare inflammatory heart conditions than vaccination.
The study was led by the University of Cambridge, in collaboration with experts from University College London, the University of Edinburgh, and the British Heart Foundation. It covered the period from 1 January 2020 to 31 December 2022, during which 3.9 million children had a first recorded Covid diagnosis and 3.4 million received the Pfizer-BioNTech vaccine.
The two main conditions reviewed were myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the lining around the heart). Both are considered uncommon in children, but have remained under close medical observation during and after the pandemic.
The findings showed 2.24 extra cases of myocarditis or pericarditis per 100,000 children following COVID-19 infection, with elevated risk lasting up to a year. In vaccinated children, there were 0.85 extra cases per 100,000, and the increased risk generally faded within a month.
Dr Alexia Sampri, the study’s principal author from the University of Cambridge, said the results showed that while these conditions were rare, young people were more likely to experience heart, vascular, or inflammatory problems after infection than after vaccination, and for a longer duration.
Co-author Prof Angela Wood stressed the importance of tracking risks over time, especially as new variants emerge and immunity patterns shift.