Blood-clotting condition cerebral venous thrombosis (CVT), which can cause serious neurological damage, is significantly associated with mRNA Covid vaccination, a major study in leading medical journal Vaccines has found.
The research team analysed 1,154,023 adverse event reports from more than 130 countries logged with VigiBase, the World Health Organisation’s global deduplicated database, and found a “potential safety signal for CVT occurrence after COVID-19 mRNA vaccination”.
The authors note many reports were in younger people and the conditions were serious: “CVTs were commonly reported in patients aged 18-44 and 45-64 years, more frequently in women, and mainly in Europe and America… More than 90% of the patients were in serious condition, and 33% did not recover or died.”
The researchers take into account under-reporting to produce estimates of increased risk above a baseline: around 3.5 times greater risk for mRNA vaccines and seven times greater risk for AstraZeneca. This means the CVT risk from mRNA vaccines, while high, is around half that of AstraZeneca.
They also found that CVT following mRNA vaccination is only around a third as deadly as that following AstraZeneca vaccination. This means mRNA vaccines lead to deadly CVT around a sixth as often as AstraZeneca, which may explain why the condition is particularly associated with the AstraZeneca jab.
The researchers cite earlier studies to suggest the mechanism relates to the spike protein binding to the wall of blood vessels, particularly in the brain, and activating clotting mechanisms.