Rare Blood Clot From J&J, Astra Covid Shots Tied to Genetics (1)

Rare but deadly blood clots tied to Johnson & Johnson and AstraZeneca Plc’s Covid-19 shots were caused by an autoimmune reaction that some people are predisposed to, researchers found, a discovery that they say will shape development of future vaccines.

Adenovirus-based vaccines, like the J&J and AstraZeneca shots that were later pulled from the market, contain a component that, in genetically susceptible people, can trigger the production of unusually structured antibodies against a protein involved in blood clotting, scientists said Wednesday in a letter to the New England Journal of Medicine. Researchers plan to identify the culprit and ...