Scientists Unravel Rare Blood Clot Cause

A rare and dangerous condition, vaccine-induced immune thrombocytopenia and thrombosis (VITT), linked to specific COVID-19 vaccines has had its cause revealed. Scientists have pinpointed that VITT occurs when the immune system mistakenly targets platelet factor 4, a body protein. This happens due to an unusually sticky antibody that forms large immune complexes, leading to dangerous blood clots.

An international research collaboration has uncovered that patients with VITT share a distinctive antibody pattern. These antibodies initially target an adenoviral protein called protein VII, likely stemming from prior common adenovirus infections. A crucial genetic mutation within these antibodies allows them to bind extremely tightly to platelet factor 4.

This discovery explains why VITT is so rare, requiring two unlikely events: inheriting a specific immune gene variant and a rare mutation in antibody-producing cells. Understanding this mechanism is vital, as adenovirus-based vaccines remain important tools for future pandemics. The findings may also help identify similar syndromes not linked to vaccination and modify future vaccine designs to prevent such rare immune responses.