AstraZeneca said on Thursday its COVID-19 vaccine was 76 percent effective at preventing symptomatic illness and completely stopped severe or critical forms of the disease, citing a new analysis of up-to-date results for its major US trial.
US health officials earlier in the week publicly rebuked the drugmaker for using "outdated information" when calculating that the vaccine was 79 percent effective.
That marked a new setback for the vaccine that was once hailed as a milestone in the fight against the COVID-19 pandemic, but has been dogged by questions over its effectiveness and possible side-effects.
Confidence in the vaccine took a further hit this month when more than a dozen countries, mostly in Europe, temporarily suspended the shot after reports linked it to a rare blood clotting disorder in a very small number of people.
AstraZeneca had also said on Monday an interim analysis of data showed that the shot, developed with Oxford University, was 100 percent effective against severe or critical forms of the disease.