A large-scale study published in The Lancet Child & Adolescent Health has found that children and young people face substantially higher risks of rare vascular and inflammatory complications following COVID-19 infection compared with COVID-19 vaccination. The research, led by Alexia Sampri of the University of Cambridge, analysed health records from nearly 14 million children in England.
The retrospective, population-based cohort study included 98% of individuals aged 18 or younger in England between January 2020 and December 2022. Of the 13.9 million participants, 3.9 million had received a COVID-19 diagnosis, whilst 3.4 million had been vaccinated with the BNT162b2 vaccine. Researchers examined de-identified electronic health records for five conditions: arterial thrombotic events, venous thrombotic events, thrombocytopenia, myocarditis or pericarditis, and inflammatory conditions.
Following a COVID-19 diagnosis, risks for all five conditions were elevated, particularly during the first four weeks. In the first week after diagnosis, adjusted hazard ratios were 2.33 for arterial thromboembolism, 4.90 for venous thromboembolism, 3.64 for thrombocytopenia, 3.46 for myocarditis or pericarditis, and 14.84 for inflammatory conditions. Although these risks declined over time, they remained elevated beyond 12 months for venous thromboembolism, thrombocytopenia, and myocarditis or pericarditis.
In contrast, vaccination was associated with an increased risk of myocarditis or pericarditis only, with an adjusted hazard ratio of 1.84 within the first four weeks. This risk returned to baseline levels thereafter. Over six months, COVID-19 infection resulted in an estimated 2.24 additional cases of myocarditis or pericarditis per 100,000 children, compared with just 0.85 extra cases per 100,000 following vaccination.
The authors concluded that these findings support public health strategies promoting COVID-19 vaccination in children and young people to mitigate the more frequent and persistent risks associated with infection.
Source: Physicians Weekly / University of Cambridge (The Lancet Child & Adolescent Health, 2025)
