Genetic Variant Linked to Rare Clotting After Some COVID Vaccines

A Nature study traces vaccine-induced immune thrombocytopenia and thrombosis (VITT) to a genetic mutation in antibody-producing cells that alters antibodies to bind PF4 after exposure to an adenovirus used in some COVID vaccines (AstraZeneca/J&J). This explains why rare clotting occurred in a subset of recipients and suggests a genetic predisposition, though not all carriers develop VITT; the researchers analyzed samples from 21 affected individuals and showed the mutated antibodies drive more clots in animal tests.