A Phase III trial of the AstraZeneca vaccine in the US has demonstrated the shot is 79 per cent effective at preventing symptomatic COVID-19.
Further, the vaccine has been proven to be 100 per cent effective at preventing severe disease and hospitalisation for those infected by COVID-19.
Importantly, in participants aged 65 years and over, vaccine efficacy was 80 per cent.
The interim safety and efficacy analysis was based on 32,499 participants accruing 141 symptomatic cases of COVID-19, with efficacy consistent across ethnicity and age.
"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," University of Rochester School of Medicine Professor of Medicine Ann Falsey said.
"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."
The trial showed the vaccine was well tolerated, and an independent data safety monitoring board (DSMB) identified no safety concerns relating to the vaccine.
Following reports in Europe that the vaccine was causing blood clots in a small number of those that received the jab, the DSMB conducted a specific review of thrombotic events.
The DSMB found no increased risk of thrombosis or events categorised by thrombosis among the 21,583 participants that received at least one dose of the vaccine.
AstraZeneca executive vice president of BioPharmaceuticals R&D Mene Pangalos says these results from the US add to a growing body of evidence that shows the vaccine is well tolerated and highly effective.
"We are confident this vaccine can play an important role in protecting millions of people worldwide against this lethal virus," says Pangalos.
"We are preparing to submit these findings to the US Food and Drug Administration and for the rollout of millions of doses across America should the vaccine be granted US Emergency Use Authorization."
The results come days after the Australian Therapeutic Goods Administration (TGA) gave biotech company CSL (ASX: CSL) approval for the company's subsidiary Seqirus to manufacture the AstraZeneca vaccine.
It also comes as Australia's vaccine program is scaled up, with Phase 1B of the rollout commencing yesterday.
Updated at 9.56am AEDT on 23 March 2021.
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