WASHINGTON (AFP) - AstraZeneca's Covid-19 vaccine is 80 per cent effective at preventing the disease in the elderly and does not increase the risk of blood clots, the biotech firm said on Monday (March 22), following its United States phase three efficiency trials.
It was 79 per cent effective at preventing symptomatic Covid-19 in the overall population and 100 per cent effective at preventing severe disease and hospitalisation, it said. Several countries had advised against administering the jab to older people due to a lack of data among elderly participants in previous trials.
Earlier this month, several countries also paused use of the AstraZeneca shot over fears it may cause blood clots.
The United States phase three trial of the vaccine developed by AstraZeneca and Oxford University involved 32,449 participants, with two-thirds receiving the jab, the pharmaceutical firm said in a statement.
Around 20 per cent were 65 or older, and about 60 per cent had health conditions associated with a higher risk of severe Covid-19, such as diabetes, severe obesity or cardiac disease.
"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 professor of medicine Ann Falsey at the University of Rochester School of Medicine. She is the trial's co-lead principal investigator.
"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's independent data safety monitoring board found no increased risk of thrombosis among the 21,583 participants who received at least one dose, the statement said.
Some leading European Union countries have resumed AstraZeneca vaccinations after the European Medicines Agency said last Thursday that the jab was "safe and effective" and was not linked to an increased risk of blood clots.
AstraZeneca said it was preparing to submit its findings to the US Food and Drug Administration to authorise the shot for emergency use.
"These results add to the growing body of evidence that shows this vaccine is well-tolerated and highly effective against all severities of Covid-19 and across all age groups," said Mr Mene Pangalos, executive vice-president of biopharmaceuticals research and development at AstraZeneca.
"We are confident this vaccine can play an important role in protecting millions of people worldwide against this lethal virus."
The results also suggested that administering the second shot more than four weeks after the first could further increase efficacy. Previous trials have shown leaving up to 12 weeks between jabs increased its efficacy.