Copenhagen (Agencies): A comprehensive study of nearly 100 million people across eight countries has revealed a higher than expected incidence of side effects from various COVID-19 vaccines, according to the Global Vaccine Data Network (GVDN). The study, which was published in the medical journal Vaccine, examined 13 neurological, blood, and heart-related conditions, termed “adverse events of special interest.”
The lead author of the study, Kristyna Faksova from the Statens Serum Institut in Copenhagen, Denmark, stated that the large population size of the study increased the possibility of identifying rare potential vaccine safety signals.
The study found a higher incidence of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the heart sac) among recipients of the Pfizer/BioNTech and Moderna vaccines than expected. Moderna’s vaccine also showed a higher rate of acute disseminated encephalomyelitis (ADEM), an inflammation and swelling in the brain and spinal cord.
Safety signals for myocarditis were consistently identified following the first three doses of either mRNA vaccine, with the highest ratio after the second dose. Signals for pericarditis were also observed following the first and fourth doses of the Moderna vaccine and after a third dose of the Oxford/AstraZeneca vaccine.
Recipients of the Oxford/AstraZeneca vaccine had more observed events of Guillain-Barré Syndrome (GBS) and cerebral venous sinus thrombosis (CVST, a type of blood clot in the brain) than expected.
The GVDN has made the results publicly available on its interactive data dashboards, cautioning the public not to overinterpret correlations and affirming that the vaccines are both safe and effective. The study was part of the GVDN’s Global COVID Vaccine Safety Project and was fully funded by a $10 million grant from the US Centers for Disease Control and Prevention (CDC).