Age-Stratified Risk of Cerebral Venous Sinus Thrombosis After SARS-CoV-2 Vaccination

Background and Objectives Cerebral venous sinus thrombosis (CVST) as a part of the thrombosis and thrombocytopenia syndrome is a rare adverse drug reaction of severe acute respiratory syndrome coronavirus disease 2 (SARS-CoV-2) vaccination. Estimated background rate of CVST with thrombocytopenia is 0.1 per million per month. We assessed the age-stratified risk of CVST with and without thrombocytopenia after SARS-CoV-2 vaccination. Methods We estimated the absolute risk of CVST with and without thrombocytopenia within 28 days of a first dose of 4 SARS-CoV-2 vaccinations using data from the European Medicines Agency's EudraVigilance database (until June 13, 2021). As a denominator, we used data on vaccine delivery from 31 European countries. For 22.8 million adults from 25 countries, we estimated the absolute risk of CVST after the first dose of ChAdOx1 nCov-19 per age category. Results The absolute risk of CVST within 28 days of first-dose vaccination was 7.5 (95% confidence interval [CI] 6.9-8.3), 0.7 (95% CI 0.2-2.4), 0.6 (95% CI 0.5-0.7), and 0.6 (95% CI 0.3-1.1) per million of first doses of ChAdOx1 nCov-19, Ad26.COV2.S, BNT162b2, and mRNA-1273, respectively. The absolute risk of CVST with thrombocytopenia within 28 days of first dose vaccination was 4.4 (95% CI 3.9-4.9), 0.7 (95% CI 0.2-2.4), 0.0 (95% CI 0.0-0.1), and 0.0 (95% CI 0.0-0.2) per million of first doses of ChAdOx1 nCov-19, Ad26.COV2.S, BNT162b2, and mRNA-1273, respectively. In recipients of ChAdOx1 nCov-19, the absolute risk of CVST, both with and without thrombocytopenia, was the highest in the 18- to 24-year-old group (7.3 per million, 95% CI 2.8-18.8 and 3.7 per million, 95% CI 1.0-13.3, respectively). The risk of CVST with thrombocytopenia in ChAdOx1 nCov-19 recipients was the lowest in the age group >= 70 years (0.2, 95% CI 0.0-1.3). Age <60 years compared to >= 60 years was a predictor for CVST with thrombocytopenia (incidence rate ratio 5.79, 95% CI 2.98-11.24, p < 0.001). Discussion The risk of CVST with thrombocytopenia within 28 days of first-dose vaccination with ChAdOx1 nCov-19 was higher in younger age groups. The risk of CVST with thrombocytopenia was slightly increased in patients receiving Ad26.COV2.S compared with the estimated background risk. The risk of CVST with thrombocytopenia was not increased in recipients of SARS-CoV-2 mRNA vaccines.

Automated summary

This study assessed the age-stratified risk of cerebral venous sinus thrombosis (CVST) with and without thrombocytopenia after SARS-CoV-2 vaccination. The absolute risk of CVST within 28 days of vaccination was highest in the 18-24-year-old age group, and the risk of CVST with thrombocytopenia was slightly increased in patients receiving the Ad26.COV2.S vaccine compared to the estimated background risk. However, there was no increased risk of CVST with thrombocytopenia in recipients of SARS-CoV-2 mRNA vaccines.