Ángel Hernández Merino
Pediatrician and collaborator of the Advisory Committee on Vaccines, the Spanish Association of Pediatrics and the Spanish Association of Primary Care Pediatrics
This study quantifies and compares the incidence and risks of serious adverse events of a vascular and inflammatory nature following the first COVID infection and following vaccination with Pfizer's RNA product in children and adolescents.
Although it is a retrospective observational study, it is valuable because it is based on the electronic records of virtually the entire population (approximately 14 million) of children under 18 years of age between January 2020 and December 2022.
The study confirms, first, that both scenarios—infection versus non-infection or prior to infection; and vaccination versus non-vaccination or prior to vaccination—are associated with serious but rare or very rare adverse events. And second, that the risks are substantially lower after vaccination compared to those associated with the first COVID infection.
COVID infection caused an increased risk of arterial or venous thromboembolism, thrombocytopenia, myocarditis/pericarditis and other inflammatory conditions for several weeks, even up to 12 months. COVID vaccination was associated with a risk of myocarditis/pericarditis during the 4 weeks following vaccination (1.84 cases/100,000 vaccinated). Over a 6-month period, the risks of myocarditis/pericarditis were 2.24 additional cases (per 100,000) for COVID infection and 0.85 additional cases/100,000 for vaccination.
Given that the risk of exposure to COVID-19 and, therefore, of infection is estimated to be very high, and that it is practically impossible to avoid repeated exposure to the virus, the data provided by this study are important for health authorities and professionals when recommending and facilitating vaccination for children and young people. The data are also valuable when informing young people and their families about the benefits and risks associated with vaccination as opposed to those of infection. The data shown by the study could be applicable to our population.