Researchers discover how vaccine-induced immune thrombotic thrombocytopenia happens A McMaster University team of researchers recently discovered how, exactly, the COVID-19 vaccines that use adenovirus vectors trigger a rare but sometimes fatal blood clotting reaction called vaccine-induced immune thrombotic thrombocytopenia or VITT. The findings will put scientists on the path of finding a way to better diagnose and treat VITT, possibly prevent it and potentially make vaccines safer. The researchers' article was fast-tracked for publication today by the prestigious journal Nature in its accelerated article preview because of the importance of the research. Our work also answers important questions about the connection between antibodies and clotting."