Risk for Cerebral Venous Thrombosis Elevated After COVID-19 Diagnosis

By Kelly Young

Edited by André Sofair, MD, MPH, and William E. Chavey, MD, MS

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higher among people with COVID-19 than in the general population or in mRNA vaccine recipients, suggests an unpublished study. (Of note, health officials have said that what is unusual about recent observations of thrombotic events with COVID-19 adenovirus-vectored vaccines — which led to a recommended pause for the Johnson & Johnson vaccine in the U.S. — is the higher rate of CVT with thrombocytopenia. This study did not directly address that aspect.)

Using electronic health records, researchers at Oxford University examined the incidence of CVT among roughly 500,000 patients diagnosed with COVID-19, nearly 500,000 who'd received the first dose of a COVID-19 mRNA vaccine, and roughly 175,000 with influenza diagnosed between January 2020 and March 2021.

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've 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: "The current data highlight the risk of serious thrombotic events in COVID-19, and can help contextualize and inform debate about the risk-benefit ratio for current COVID-19 vaccines."