In a late-night news release Wednesday, AstraZeneca said it had analyzed more data from that study and concluded the vaccine is 76% effective in preventing symptomatic COVID-19, instead of the 79% it had reported earlier in the week.
The updated information "confirms that our COVID-19 vaccine is highly effective in adults, including those aged 65 years and over", AstraZeneca research chief Mene Pangalos said in a statement.
AstraZeneca had been counting on findings from a predominantly U.S. study of 32,000 people to help rebuild confidence in a vaccine that, despite being widely used in Britain, Europe and other countries, has had a troubled rollout. Previous studies have turned up inconsistent data about its effectiveness, and then last week a scare over blood clots had some countries temporarily pausing inoculations. That determination led most countries that had put a pause on the vaccine to resume immunizations with it.
Among the elderly, among whom no cases of the rare side effect have been reported, and who are at a so much higher risk of becoming seriously ill with Covid-19, he said, the benefits were much, much greater than any risk.
"The public should be reassured by the fact that over 20 million doses of this vaccine have been given in the EEA and the United Kingdom providing protection to those who have received it".
European Union attacks on AstraZeneca call into question its decision not to profit from its coronavirus vaccine, according to a leading member of the scientific team that delivered the breakthrough.
The company intends to seek Food and Drug Administration clearance of the vaccine within a few weeks.
According to the European Center for Disease Prevention and Control, more than 1 million doses of various vaccines have been administered in Denmark, which has a population of almost 6 million.
Approximately 150,000 people had already received AstraZeneca's shot in Denmark before it was suspended.
"We believe it's good and necessary to have a bit more knowledge about how rare it is, and how we need to deal with it, and if it's possible to find risk factors behind it so that we can avoid [these events], because they are very, very serious and often fatal".
The Niti Aayog official emphasised that both vaccines - Covishield and Covaxin - now in use in India were effective against the Brazilian and United Kingdom strains.
Sir John said: "I haven't got a problem with people making money but there's a time and a place".
There's a point at which AstraZeneca could just say, 'you've got to be joking, we're going to stop [charging cost price] now because we're not getting any credit for what we're doing. "That is why we have made a decision to extend the break".
However, both the EMA and the National Public Health Emergency Team (NPHET) recommended that the use of the vaccine should continue after a conclusion by the former that the vaccine is "safe and effective".