A British-Swedish pharma company, AstraZeneca, announced on Thursday that its COVID-19 vaccine, which was developed in collaboration with Oxford University, has been found to increase the risk of developing a rare but life-threatening blood clotting disorder known as vaccine-induced immune thrombocytopenia and thrombosis (VITT). The issue lies in an unusually dangerous blood autoantibody that targets a protein called platelet factor 4 (PF4).
VITT is not a new condition, but it emerged as a new disease after the administration of the Oxford-AstraZeneca vaccine, known as Covishield in India and Vaxzevria in Europe, during the height of the COVID-19 outbreak in 2021. Research conducted in 2023 by scientists from Canada, North America, Germany, and Italy revealed an almost identical condition with the PF4 antibody, which turned out to be fatal in some cases after contracting a natural adenovirus infection, which is commonly associated with the common cold.
A new study conducted by Australia’s Flinders University and other experts has shown that the PF4 antibodies in adenovirus infection-associated VITT and classic adenoviral vector VITT share similar molecular characteristics. Professor Tom Gordon from Flinders explained that the pathways of antibody production in these disorders are likely identical and have similar genetic risk factors. This finding suggests that the lessons learned from VITT in relation to the AstraZeneca vaccine can be applied to rare cases of blood clotting after adenovirus infections, which can also have implications for vaccine development.
On Thursday, AstraZeneca reported that its COVID-19 vaccine was successful in lowering the risk of infection among people with weakened immune systems, meeting the primary goal of its late-stage trial. The company’s long-acting antibody therapy, sipavibart, was found to cause a “statistically significant reduction” in symptomatic COVID-19 cases among immunocompromised patients, according to Reuters. Iskra Reic, the company’s Executive Vice President for Vaccines and Immune Therapies, emphasized the importance of this finding for immunocompromised individuals who have limited or no options for COVID-19 protection and continue to face a significant burden of disease despite often being fully vaccinated. The company plans to collaborate with regulatory authorities worldwide to make sipavibart available to these vulnerable populations.
