AstraZeneca’s COVID-19 vaccine, in collaboration with Oxford University, has been found to increase the risk of a rare but deadly blood clotting disorder known as vaccine-induced immune thrombocytopenia and thrombosis (VITT). The condition, characterized by the presence of a specific blood autoantibody targeting platelet factor 4 (PF4), was initially observed following the administration of the Oxford-AstraZeneca vaccine, also known as Covishield in India and Vaxzevria in Europe. Researchers have since discovered that PF4 antibodies can also trigger VITT in cases of natural adenovirus infections. AstraZeneca has also announced positive results from a late-stage trial of sipavibart, a long-acting antibody therapy that has shown promise in reducing the risk of infection among immunocompromised individuals.