A phase 3 trial of the AstraZeneca vaccine candidate in the United States has revealed an efficacy of 79%, when both doses were administered 4 weeks apart. This is a significant jump over the candidate’s efficacy reported in the earlier trial conducted in the U.K., Brazil and South Africa.
AstraZeneca reported results of the trial via a press release on Monday and a formal scientific publication is awaited.
The finding adds confidence to the Covishield vaccine, which is the same as the AstraZeneca vaccine. Results on Covishield trials done specifically on Indian participants aren’t yet available.
‘No safety concerns’
The U.S. trial, which recruited over 32,000 volunteers across all age groups, showed that the vaccine is 79% effective against symptomatic COVID-19, and 100% effective against severe, or critical symptomatic COVID-19. The independent Data and Safety Monitoring Board (DSMB) reported no safety concerns among the participants receiving at least one dose of the vaccine, AstraZeneca said in a statement.
Andrew Pollard, professor of Paediatric Infection and Immunity, and lead investigator of the Oxford University trial of the vaccine, said: “These results are great news as they show the remarkable efficacy of the vaccine in a new population and are consistent with the results from Oxford-led trials. We can expect strong impact against COVID-19 across all ages and for people of all different backgrounds from widespread use of the vaccine.”
Sarah Gilbert, professor of Vaccinology, and co-designer of the ChAdOx1 nCov-19 coronavirus vaccine, said: “These new results from the large phase III trials in the U.S., Chile and Peru provide further confirmation of the safety and effectiveness of ChAdOx1 nCoV-19.”
AstraZeneca will be submitting the data for analysis by the scientific community in peer-review literature, and to the regulators in the U.S., the U.S. Food and Drugs Administration (FDA) and for emergency approval for use.


