The US trial data showed that the vaccine’s efficacy of 79% was achieved when two standard doses were given at an interval of four weeks; while data from UK trials showed an efficacy of 53% for interval of less than six weeks.
NEW DELHI: In a move that may provide a boost for AstraZeneca plc’s covid-19 vaccine, the company on Monday; said the jab showed an efficacy of 79% in phase 3 trial in the US, Chile and Peru; much higher than the results from the UK trial announced in November.
Interestingly, the US trial data showed that the vaccine’s efficacy of 79%; was achieved when two standard doses were given at an interval of four weeks; while data from UK trials showed an efficacy of 53% for interval of less than six weeks.
In UK and Brazil, the efficacy was an average of 62%. Due to some errors by Oxford researchers in the US; the actual efficacy varied between 53% and 90%, depending on the amount of dosage given and the interval between two doses.
The interval varied between four weeks and 12 weeks.
In the US trial, the analysis was based on 32,449 participants, including 141 symptomatic cases of COVID-19.
The participants were randomised 2:1 with twice as many participants getting the vaccine as compared to the placebo group.
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The Anglo-Swedish drugmaker said the result was consistent across ethnicity and age with vaccine efficacy; being 80% among participants aged 65 years and over.
The trials in UK had limited efficacy data for the elderly due to the small number of cases.
“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,” said Ann Falsey, professor of medicine at University of Rochester School of Medicine and co-lead principal investigator for the trial.
AstraZeneca said it will prepare to submit the primary analysis to the US Food and Drug Administration; for emergency use authorization in the coming weeks and will also submit the data for publication in a peer-reviewed journal.
The covid-19 vaccine, co-developed by AstraZeneca with the University of Oxford; is also manufactured by Serum Institute of India under the brand ‘Covishield’.