No extra blood clot risk after 2nd dose of AstraZeneca shot: Study

London, July 28

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The AstraZeneca vaccine is associated with a small risk of rare blood clots after the first dose, and no extra risk after the second shot, according to a study led and funded by the British-Swedish drugmaker. The research, published in The Lancet on Tuesday, shows that the rates of the very rare clotting disorder, thrombosis with thrombocytopenia syndrome (TTS), following a second dose of the vaccine are comparable to those among unvaccinated population. TTS is a very rare syndrome which occurs when a person has blood clots (thrombosis) as well as low platelet counts (thrombocytopenia). It is also referred to as vaccine-induced immune thrombotic thrombocytopenia (VITT). Rare cases of TTS have been reported after immunisation with the AstraZeneca vaccine, known as Covishield in India, which led to several countries restricting or stopping the use of the preventive. The authors demonstrated that the estimated rate of TTS following a second dose of AstraZeneca was 2.3 per million vaccinees, comparable to the rate observed in an unvaccinated population. The rate was 8.1 per million vaccinees after the first dose, they said.PTI