LONDON

Children and young people face a higher and longer-lasting risk of rare heart and inflammatory complications after catching COVID-19 than after being vaccinated, according to new research published in The Lancet Child and Adolescent Health.

The large-scale study — the biggest of its kind in this age group — was led by scientists from the Universities of Cambridge and Edinburgh, and University College London.

Researchers analyzed electronic health records from nearly 14 million children in England under the age of 18 between January 2020 and December 2022, covering 98% of this population.

During that time, 3.9 million children had a first COVID-19 diagnosis, and 3.4 million received their first dose of the Pfizer–BioNTech vaccine — the main vaccine given to 5–18-year-olds in the study period.

The study found that while these heart and inflammatory complications were rare, the risks were much higher and longer-lasting following infection than after vaccination.

Principal author Dr. Alexia Sampri, from the Cardiovascular Epidemiology Unit at the University of Cambridge, said in a statement: “Our whole-population study during the pandemic showed that although these conditions were rare, children and young people were more likely to experience heart, vascular or inflammatory problems after a COVID-19 infection than after having the vaccine — and the risks after infection lasted much longer.”

The team examined short- and long-term risks of conditions such as myocarditis and pericarditis (inflammation of the heart and surrounding tissue), blood clots, low platelet counts, and other inflammatory complications.

After a COVID-19 diagnosis, the risks of all five conditions were highest within the first four weeks and, for some, remained elevated for up to a year.

By contrast, after vaccination, only a short-term increase in myocarditis or pericarditis was seen within the first four weeks — after which the risk returned to baseline.

Over six months, researchers estimated that infection led to 2.24 extra cases of myocarditis or pericarditis per 100,000 children and young people, compared to 0.85 extra cases per 100,000 following vaccination.

Co-author Professor Angela Wood, from the University of Cambridge and associate director at the BHF Data Science Centre, said: “Using electronic health records from all children and young people in England, we were able to study very rare but serious heart and clotting complications, and found higher and longer-lasting risks after COVID-19 infection than after vaccination.

“Whilst 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.”