AstraZeneca and Oxford University's potential COVID-19 vaccine produced a strong immune response in older adults, data published on Thursday showed, with researchers expecting to release late-stage trial results by Christmas.
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The data, reported in part last month but published in full in The Lancet medical journal on Thursday, suggest that those aged over 70, who are at higher risk of serious illness and death from COVID-19, could build robust immunity.
"The robust antibody and T-cell responses seen in older people in our study are encouraging," said Maheshi Ramasamy, a consultant and co-lead investigator at the Oxford Vaccine Group.
"We hope that this means our vaccine will help to protect some of the most vulnerable people in society but further research will be needed before we can be sure."
Late-stage, or Phase III, trials are ongoing to confirm the findings, researchers said, and to test whether the vaccine protects against infection with SARS-CoV-2 in a broad range of people, including people with underlying health conditions.
Results of those trials should definitely be known by Christmas, the Oxford Vaccine Group's director Andrew Pollard said, adding it was too early to know whether and how well the vaccine worked in preventing COVID-19 disease.
"We're obviously not going to rush that," he told BBC radio. "We're getting close, and it's definitely going to be before Christmas, based on the progress."
The Oxford-AstraZeneca COVID-19 vaccine candidate, called AZD1222 or ChAdOx1 nCoV-19, had been among the frontrunners in global efforts to develop shots to protect against infection with the novel coronavirus, or SARS-CoV-2.
But rival drug makers Pfizer, BioNTech and Moderna have in the past 10 days edged ahead, releasing data from late-stage COVID-19 vaccine trials that shows more than 90 per cent efficacy.
Unlike the Pfizer-BioNTech and Moderna shots, both of which use new technology known as messenger RNA (mRNA), AstraZeneca's is a viral vector vaccine made from a weakened version of a common cold virus found in chimpanzees.
The Phase II trial reported in The Lancet involved a total of 560 healthy volunteers, with 160 aged 18-55 years, 160 aged 56-69 years, and 240 aged 70 or over.
Volunteers got two doses of the vaccine or a placebo, and no serious side effects related to the AZD1222 vaccine were reported.
AstraZeneca has signed several supply and manufacturing deals with governments around the world, including Australia.
Australian Associated Press
