Rates of cerebral venous thrombosis (CVT), also called cerebral venous sinus thrombosis, are significantly higher among people with COVID-19 than in the general population or in mRNA vaccine recipients, suggests an unpublished study.
In patients with COVID-19, the absolute risk for CVT in the 2 weeks after diagnosis was 39 events per million people — significantly higher than the risk among influenza patients (0 per million) or mRNA vaccine recipients (4.1 per million). This was also higher than the risk among patients who have received the AstraZeneca adenovirus vaccine (5.0 per million at last count of the European Medicines Agency's monitoring system).
The incidence of portal vein thrombosis (PVT) was similarly elevated in the COVID-19 group, compared with the other groups. Mortality rates for COVID-19 patients after a diagnosis of CVT or PVT were 20% and 18%, respectively.
The authors say, "The current data highlight the risk of serious thrombotic events in COVID-19, and can help contextualise and inform debate about the risk-benefit ratio for current COVID-19 vaccines."