van Kammen MS, Heldner MR, Brodard J, et al. - Via this descriptive analysis of a retrospective consecutive sample of 865 patients with cerebral venous sinus thrombosis from 1987 to 2018, researchers aimed at determining the frequencies of thrombocytopenia, heparin-induced thrombocytopenia, and platelet factor 4/heparin antibodies in these patients prior to the COVID-19 pandemic. Observations revealed baseline thrombocytopenia in 8.4% of patients, and heparin-induced thrombocytopenia in 0.1%. In a convenience sample subset of 93 patients with plasma available for additional laboratory analysis (including 8 who had thrombocytopenia), platelet factor 4/heparin antibodies were not identified in any patient. Considering these findings, investigations could be undertaken for the possible correlation between the ChAdOx1 nCoV-19 (AstraZeneca/Oxford) and Ad26.COV2.S (Janssen/Johnson & Johnson) COVID-19 vaccines and cerebral venous sinus thrombosis with thrombocytopenia.