AstraZeneca's Covid-19 shot did not increase the instances of rare blood clots with low platelets in people after the second dose, a study showed, potentially easing some worries over the vaccine's side effects.

Data published in the Lancet medical journal found that the estimated rate of thrombosis with thrombocytopenia syndrome (TTS) after the second dose of the vaccine was 2.3 per million in those inoculated, comparable to the typical rate seen in those who have not been vaccinated, AstraZeneca said.

That rate was 8.1 after the first dose, it added.

The research, led and funded by AstraZeneca, evaluated reported cases occurring within 14 days of administration of the first or second dose as of April 30, using the Anglo-Swedish drugmaker's global safety database, according to Reuters.