CHICAGO - According to AstraZeneca Plc's recently published clinical trial, the COVID-19 vaccine showed 74 per cent efficacy at preventing symptomatic disease, a figure that increased to 83.5 per cent in people aged 65 and above.
Overall efficacy of 74 per cent remained lower than the interim 79 per cent reported by the British drugmaker in March. The result has been later revised to 76 per cent, after a rare public criticism from health officials that figures were based on 'outdated information'.
The recent data was based on 26,000 volunteers in the United States, Chile and Peru, who received two vaccine doses a month apart. The New England Journal of Medicine first held these results.
There were no cases of serious or critical symptomatic COVID-19 among more than 17,600 participants who got the Astrazeneca vaccine, compared to eight patients among the 8,500 volunteers who got the placebo. Also, there were two deaths in the placebo group but none among those who received the vaccine.
Moreover, there were no cases of rare but severe blood clotting side effects that have been linked to the AstraZeneca vaccine developed by Oxford University researchers.
