New findings on rare cerebral vein thromboses after AstraZeneca vaccination

24.9.2021

This is what scientists from the Greifswald University Hospital found out in a study with 35 patients led by transfusion specialist Andreas Greinacher. “The dangerous anti-PF4 antibodies, which can lead to cerebral vein thromboses after an AstraZeneca vaccination against Covid-19, disappear within three months in most patients. Those affected can be vaccinated a second time without the risk of the antibodies being formed again,” says Greinacher. “Therefore, a three-month interval before the second vaccination is clearly recommended.” The study participants included 27 women and 8 men. The youngest patient was 18 years old, the oldest 77 years old. The patients’ clinical symptoms appeared between the 5th and the 18th day after the first vaccination. All patients had thrombocytopenia, 30 of them had thrombosis. Anti-PF4 antibodies could no longer be detected in two thirds of the patients after eleven weeks. After more than 12 weeks, the platelet activating antibodies had disappeared in most of the patients (93%). However, a complete seroconversion was only observed in three patients. In one patient, anti-PF4 antibodies remained detectable for more than 12 weeks. He suffered from recurrent episodes of thrombocytopenia. Five of the patients received the mRNA vaccine BNT162b2 (Pfizer-BioNTech) as a second vaccination 10 to 18 weeks after their first vaccination. During this time, they were still on anticoagulant medication. No clinically symptomatic new thrombotic complications occurred in any of the patients. It is unclear whether these patients should receive extended anticoagulation or additional treatment. To this end, more extensive studies are necessary