A new study has suggested that a single dose of Pfizer's Covid-19 vaccine triggers fewer heart issues in children than a natural infection with the virus. This finding addresses long-standing concerns among experts regarding myocarditis, an extremely rare vaccine complication causing inflammation of the heart muscle, and pericarditis, inflammation of the lining around the heart, particularly noted in young people, especially boys.

British researchers conducted a comprehensive study involving the health records of almost 14 million children between January 1, 2020, and December 31, 2022. During this period, approximately 3.9 million youngsters were diagnosed with Covid-19, while 3.4 million received their first dose of the Pfizer–BioNTech vaccine. The research estimated that over a six-month period, Covid-19 infections led to 2.24 extra cases of myocarditis or pericarditis per 100,000 children. In stark contrast, the figure for those who received one dose of the vaccine stood at a substantially lower 0.85 extra cases per 100,000. These findings, published in The Lancet Child and Adolescent Health, were described as “of great importance” and supportive of the public health strategy of Covid vaccination in children.

The study also examined the risk of other rare complications, including thrombocytopenia (low blood platelets) and arterial and venous thrombosis (blood clots). Researchers found that youngsters had a higher risk of these conditions for up to 12 months after being diagnosed with the virus. Conversely, after Covid-19 vaccination, the team observed only a short-term elevated risk of myocarditis or pericarditis, limited to the first four weeks post-vaccination, after which the risk returned to pre-vaccination levels.

Experts weighed in on the significance of the results. Professor Angela Wood, a cardiovascular expert at the University of Cambridge and study co-author, noted that