A major new study has found that children and teenagers face a higher and longer-lasting risk of heart inflammation and other rare complications after catching COVID-19 than after getting vaccinated.
The research, published in The Lancet Child and Adolescent Health, is the largest study of its kind and analyzed data from nearly 14 million young people in England.
The study was led by scientists from the University of Cambridge, University of Edinburgh, and University College London, with support from the British Heart Foundation Data Science Center.
Researchers examined medical records covering 98% of England’s population under 18 between January 2020 and December 2022—a period that included both the height of the pandemic and widespread vaccine rollout.
Among the 14 million children and adolescents, about 3.9 million were diagnosed with COVID-19, and 3.4 million received at least one dose of the Pfizer-BioNTech vaccine, which was the main COVID-19 vaccine given to 5–18-year-olds in the UK at that time.
The scientists investigated rare but serious complications, including heart inflammation (myocarditis and pericarditis), blood clots (thrombosis), low platelet counts (thrombocytopenia), and general inflammatory conditions.
They compared how often these issues occurred after infection versus after vaccination, using securely anonymized NHS records.
The results were clear: the risk of developing these conditions was much higher and lasted much longer after COVID-19 infection than after vaccination.
Following infection, the risk of heart or vascular complications peaked in the first four weeks and, for some conditions, remained elevated for up to a year. In contrast, after vaccination, only a brief rise in heart inflammation was seen during the first four weeks, after which the risk returned to normal.
Over a six-month period, researchers estimated that COVID-19 infection led to about 2.2 extra cases of myocarditis or pericarditis per 100,000 children, compared with 0.85 extra cases per 100,000 among those who were vaccinated.
Although these events remain rare, the findings show that infection carries a greater and longer-term risk.
“Although these conditions were rare, children and young people were more likely to experience heart or inflammatory problems after COVID-19 than after vaccination—and the risks after infection lasted much longer,” said Dr. Alexia Sampri from the University of Cambridge, the study’s lead author.
The researchers emphasized that their findings can help parents and healthcare providers make more informed decisions.
“Parents have faced difficult choices throughout the pandemic,” said Professor Pia Hardelid from University College London. “By providing clearer evidence on both infection and vaccination, we hope to support those decisions with stronger data.”
Professor Angela Wood, another co-author from Cambridge, added that continuous monitoring remains crucial as new variants appear and immunity changes over time.
“Vaccine-related risks are short-lived and rare,” she said, “but infection-related risks can persist, making vaccination an important tool for protecting young people’s long-term heart health.”
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