AstraZeneca said on Monday that a US trial of the coronavirus vaccine it has developed with the University of Oxford showed it is 79% effective at preventing symptomatic Covid-19 and 100% effective at preventing severe disease and hospitalisation.
News of the trial results comes after several European countries suspended the use of the vaccine in recent weeks due to concerns about blood clots.
The interim safety and efficacy analysis was based on 32,449 participants accruing 141 symptomatic cases of Covid-19 and the trial had a 2:1 randomisation of vaccine to placebo.
Vaccine efficacy was consistent across ethnicity and age, the company said, adding that in participants aged 65 years and over, efficacy was 80%.
AstraZeneca said the vaccine was well tolerated, and the independent data safety monitoring board (DSMB) identified no safety concerns related to the vaccine. More specifically, there were no safety issues regarding blood clots.
“The DSMB found no increased risk of thrombosis or events characterised by thrombosis among the 21,583 participants receiving at least one dose of the vaccine,” the pharmaceuticals company said.
Ann Falsey, Professor of Medicine at the University of Rochester School of Medicine, US, and co-lead Principal Investigator for the trial, said: “These findings reconfirm previous results observed in AZD1222 trials across all adult populations but it’s exciting to see similar efficacy results in people over 65 for the first time.
“This analysis validates the AstraZeneca Covid-19 vaccine as a much-needed additional vaccination option, offering confidence that adults of all ages can benefit from protection against the virus.”
