COVID-19 infection poses higher, longer heart risks to children than vaccination
A comprehensive analysis of English health records finds higher risk of rare heart complications in children and adolescents who caught COVID-19 compared to those who received an mRNA-based COVID vaccine.
- 5 November 2025
- 5 min read
- by Linda Geddes
Key points:
- Despite early reports of rare heart inflammation after COVID-19 vaccination, this major study of nearly 14 million children in England found that infection with the virus itself was far more likely to trigger serious heart, clotting and inflammatory conditions in the months that followed.
- These risks also lasted much longer than any seen after vaccination.
- The researchers said their findings supported continued vaccination in children and young people as an effective strategy to mitigate the more frequent and persistent risks associated with catching COVID-19.
As reports of rare heart inflammation in young people after COVID-19 vaccination gained traction during the early months of the pandemic, many parents understandably worried about the risks.
Now one of the largest studies to date has provided reassuring clarity: children and adolescents were far more likely to experience rare but serious heart and inflammatory conditions after a COVID-19 infection than after being vaccinated – and the risks after infection lasted much longer.
“I want to stress that these serious complications are really rare in children and young people overall,” said study co-author Prof Angela Wood at the University of Cambridge, UK. “But in this data, using the first two years of the pandemic, we can see that the risks of serious complications were generally higher and lasted for longer after a COVID-19 infection than after a vaccination.”
What’s the relationship between COVID-19 vaccines and myocarditis?
Concerns about rare cases of myocarditis and pericarditis – inflammation of the heart muscle and the tissue surrounding it – began to surface in 2021, as vaccination programmes expanded to include younger age groups, particularly mRNA-based vaccines. At the same time, growing evidence suggested that COVID-19 infection itself could trigger these, and other heart complications.
Yet, most research to date has focused on short-term outcomes and has not directly compared the long-term cardiovascular and inflammatory risk of infection versus vaccination in a large population of children and adolescents.
“The real strength and value of this study is the power of long-term follow-up for children and young people in this pandemic situation,” said co-author Professor Pia Hardelid at University College London and the UK’s National Institute of Health and Care Research Great Ormond Street Hospital Biomedical Research Centre.
What did the researchers do?
The new study, published in The Lancet Child and Adolescent Health, analysed anonymised electronic health records for nearly 14 million under-18s in England between 1 January 2020 and 31 December 2022 – around 98% of the country’s ethnically diverse child population.
Over that period, 3.9 million children and young people had a first diagnosis of COVID-19, while 3.4 million received a first dose of the Pfizer/BioNTech vaccine (BNT162b2) – the main COVID-19 vaccine offered to 5- to 18-year-olds in England at the time.
The study tracked the risks of developing rare complications after either COVID-19 infection or vaccination, including blood clots, low platelet counts (fragments that help blood to clot), myocarditis or pericarditis, and other inflammatory disorders.
What did the researchers find?
For myocarditis and pericarditis – which affect roughly five in every 100,000 children each year – COVID-19 was linked to an extra 2.24 cases per 100,000 children in the six months after infection, with the risk remaining slightly elevated for almost a year.
Among vaccinated children, however, researchers saw a smaller and shorter-term increase in risk – equivalent to 0.85 extra cases per 100,000 individuals – over six months. That small risk was mostly confined to the first four weeks after vaccination, after which it returned to baseline. There was no evidence of any long-term heart inflammation after vaccination.
The study also identified a significant increase in venous thromboembolisms – a type of blood clot in the veins – particularly in the week after COVID-19 diagnosis, but no such risk after vaccination. Over six months, COVID-19 infection led to an estimated 5.6 extra blood clot cases per 100,000 children.
Similarly, abnormally low levels of platelets occurred more often after infection (2.28 additional cases per 100,000 children) but did not increase after vaccination.
Finally, the researchers also observed a sharp and prolonged rise in severe inflammatory conditions such as multisystem inflammatory syndrome in children (MIS-C) and Kawasaki disease in those who had COVID-19. By contrast, the risk of these conditions was negligible – or even slightly lower – after vaccination.
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What message should people draw from this study?
The researchers said their findings should not be used to challenge the safety and efficacy of mRNA COVID-19 vaccines in children and young people.
“Although we observed a short-term higher risk of myocarditis or pericarditis following first vaccination, these events were very rare and not sustained, whereas SARS-CoV-2 infection was associated with rare but more frequent and longer-lasting vascular and inflammatory outcomes,” they wrote.
“Taken together with extensive evidence that vaccination markedly reduces the risk of severe COVID-19, hospitalisation, and related complications, our results reinforce that the benefits of mRNA COVID-19 vaccination clearly outweigh its small risks and that these vaccines have played a critical role in protecting this population.”
They added that their findings supported continued vaccination in children and young people as an effective strategy to mitigate the more frequent and persistent risks associated with catching COVID-19.
“Policy makers and health-care providers can use these results to support informed discussions with caregivers regarding the relative safety profiles of infection and vaccination,” they said.
Wood added that while vaccine-related risks are likely to remain rare and short-lived, future risks following infection could change as new variants emerge and immunity shifts. “That’s why whole-population health data monitoring remains essential to guide vaccine and other important public health decisions,” she said.
