AstraZeneca's Covid-19 vaccine carries a small extra risk of rare blood clots with low platelets after the first dose and no extra risk after the second, a study led and funded by the drugmaker showed on Wednesday, after worries over side-effects.

The study, published in the Lancet medical journal, found that the estimated rate of thrombosis with thrombocytopenia syndrome (TTS) after the first dose was 8.1 per million in those inoculated, AstraZeneca said...