Venous sinus thrombosis after the second jab of an mRNA-based SARS-CoV-2 vaccine

OBJECTIVES: Venous sinus thrombosis (VST) after vaccination with the mRNA-based vaccine produced by Pfizer is comparatively rare and usually occurs after the first dose. VST after the second dose has been reported in only few patients. CASE REPORT: The patient is a 33yo male who experienced an episode of sudden onset focal, stabbing headache in the left temporal region for about 4 h. Three days later a similar episode occurred accompanied by a focal seizure. Twenty days before he had received the second dose of the Pfizer vaccine. Clinical exam was normal but MRI of the brain revealed a VST of the left transverse and sigmoid sinuses. Anticoagulation with low molecular weight heparin followed by dabigatran resulted in complete recovery. CONCLUSIONS: This case shows that also the second dose of the Pfizer vaccine can be followed by a VST. Currently, there are more arguments in favour of a causal relation between the vaccination and the VST than against it.