Background and purpose Cerebral venous sinus thrombosis (CVST) has been described after vaccination against SARS‐CoV‐2. The clinical characteristics of 213 post‐vaccination CVST cases notified to the European Medicines Agency are reported. Methods Data on adverse drug reactions after SARS‐CoV‐2 vaccination notified until 8 April 2021 under the Medical Dictionary for Regulatory Activities Term ‘Central nervous system vascular disorders’ were obtained from the EudraVigilance database. Post‐vaccination CVST was compared with 100 European patients with CVST from before the COVID‐19 pandemic derived from the International CVST Consortium. Results In all, 213 CVST cases were identified: 187 after AstraZeneca/Oxford (ChAdOx1 nCov‐19) vaccination and 26 after a messenger RNA (mRNA) vaccination (25 with Pfizer/BioNTech, BNT162b2, and one with Moderna, mRNA‐1273). Thrombocytopenia was reported in 107/187 CVST cases (57%, 95% confidence interval [CI] 50%–64%) in the ChAdOx1 nCov‐19 group, in none in the mRNA vaccine group (0%, 95% CI 0%–13%) and in 7/100 (7%, 95% CI 3%–14%) in the pre‐COVID‐19 group. In the ChAdOx1 nCov‐19 group, 39 (21%) reported COVID‐19 polymerase chain reaction tests were performed within 30 days of CVST symptom onset, and all were negative. Of the 117 patients with a reported outcome in the ChAdOx1 nCov‐19 group, 44 (38%, 95% CI 29%–47%) had died, compared to 2/10 (20%, 95% CI 6%–51%) in the mRNA vaccine group and 3/100 (3%, 95% CI 1%–8%) in the pre‐COVID‐19 group. Mortality amongst patients with thrombocytopenia in the ChAdOx1 nCov‐19 group was 49% (95% CI 39%–60%). Conclusions Cerebral venous sinus thrombosis occurring after ChAdOx1 nCov‐19 vaccination has a clinical profile distinct from CVST unrelated to vaccination. Only CVST after ChAdOx1 nCov‐19 vaccination was associated with thrombocytopenia.

and the Cerebral Venous Sinus Thrombosis With Thrombocytopenia Syndrome Study Group IMPORTANCE Thrombosis with thrombocytopenia syndrome (TTS) has been reported after vaccination with the SARS-CoV-2 vaccines ChAdOx1 nCov-19 (Oxford-AstraZeneca) and Ad26.COV2.S (Janssen/Johnson & Johnson).OBJECTIVE To describe the clinical characteristics and outcome of patients with cerebral venous sinus thrombosis (CVST) after SARS-CoV-2 vaccination with and without TTS. DESIGN, SETTING, AND PARTICIPANTSThis cohort study used data from an international registry of consecutive patients with CVST within 28 days of SARS-CoV-2 vaccination included between March 29 and June 18, 2021, from 81 hospitals in 19 countries. For reference, data from patients with CVST between 2015 and 2018 were derived from an existing international registry. Clinical characteristics and mortality rate were described for adults with (1) CVST in the setting of SARS-CoV-2 vaccine-induced immune thrombotic thrombocytopenia, (2) CVST after SARS-CoV-2 vaccination not fulling criteria for TTS, and(3) CVST unrelated to SARS-CoV-2 vaccination.EXPOSURES Patients were classified as having TTS if they had new-onset thrombocytopenia without recent exposure to heparin, in accordance with the Brighton Collaboration interim criteria. MAIN OUTCOMES AND MEASURES Clinical characteristics and mortality rate.RESULTS Of 116 patients with postvaccination CVST, 78 (67.2%) had TTS, of whom 76 had been vaccinated with ChAdOx1 nCov-19; 38 (32.8%) had no indication of TTS. The control group included 207 patients with CVST before the COVID-19 pandemic. A total of 63 of 78 (81%), 30 of 38 (79%), and 145 of 207 (70.0%) patients, respectively, were female, and the mean (SD) age was 45 ( 14), 55 (20), and 42 (16) years, respectively. Concomitant thromboembolism occurred in 25 of 70 patients (36%) in the TTS group, 2 of 35 (6%) in the no TTS group, and 10 of 206 (4.9%) in the control group, and in-hospital mortality rates were 47% (36 of 76; 95% CI, 37-58), 5% (2 of 37; 95% CI, 1-18), and 3.9% (8 of 207; 95% CI, 2.0-7.4), respectively. The mortality rate was 61% (14 of 23) among patients in the TTS group diagnosed before the condition garnered attention in the scientific community and 42% (22 of 53) among patients diagnosed later. CONCLUSIONS AND RELEVANCEIn this cohort study of patients with CVST, a distinct clinical profile and high mortality rate was observed in patients meeting criteria for TTS after SARS-CoV-2 vaccination.

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