A recent study has revealed that the rare but deadly blood clots associated with the Johnson & Johnson and AstraZeneca Plc’s COVID-19 vaccines are triggered by an autoimmune reaction in genetically predisposed individuals. This finding is expected to impact the development of future vaccines, according to Bloomberg. The adenovirus-based vaccines, similar to the J&J and AstraZeneca shots, contain a component that can cause blood clots in susceptible individuals.