The Covid-19 vaccine produced by the University of Oxford generates a similar immune response in both younger and older adults, according to the British pharmaceutical company AstraZeneca, and could be made available for vulnerable patients before the end of the year.
Immunogenicity blood tests carried out on a subset of older trial participants show that the vaccine triggers protective antibodies and T-cells among the elderly — one of the most at-risk age groups.
"It is encouraging to see immunogenicity responses were similar between older and younger adults and that reactogenicity was lower in older adults, where the Covid-19 disease severity is higher," an AstraZeneca spokesperson told Reuters.
"The results further build the body of evidence for the safety and immunogenicity of AZD1222," the spokesperson added, referring to the technical name of the vaccine.
Although the finding raises hope that the elderly will be able to build up some form of immunity against the disease, positive immunogenicity tests do not guarantee that the vaccine will ultimately prove safe and effective. Further analysis for this age group is required.
Details of the tests are expected to be published shortly in a clinical journal, according to The Financial Times. It did not name the publication.
This echoes data released in July that demonstrated that the vaccine had generated “robust immune responses" in a group of healthy adults aged between 18 and 55.
The Oxford vaccine, which is being manufactured by AstraZeneca, is among the leading candidates currently in development, along with doses produced by Pfizer and Moderna.
Adrian Hill, the professor leading the Oxford vaccine programme, has said medics and high-risk patients could receive doses of AZD1222 by the end of the year.
Researchers are planning to seek emergency approval for vulnerable patients once the interim data becomes available, while continuing with the large-scale phase three trials to provide further evidence, Professor Hill added.
“The initial licence would be for emergency use, not full approval,” he told members and alumni of Oxford's Magdalen College.
“They [the regulators] will want to see more data on safety and maybe efficacy before they give a licence to vaccinate everybody.
“In this country, our priorities are pretty clear ... we're going to vaccinate high-risk individuals before we vaccinate the young, the fit and healthy who are at lower risk. I think most countries will do that.
“So what we're looking for this year is an 'emergency use' authorisation that will allow us to go and vaccinate those most at risk as a priority, then early next year everybody else.”
Oxford University and AstraZeneca are currently running trials at nine sites in Britain, involving 10,000 volunteers. Further trials are being run in Brazil, South Africa, India and the US.
Once enough cases of Covid-19 have been recorded among the programme’s volunteers in the UK, scientists will then be able to ‘unblind the trial’ to see whether those infected with the virus had been given a shot of AZD1222 or not.
These data, which will demonstrate the candidate’s efficaciousness, will then be presented to regulators to be approved — or rejected if there are questions over the findings.
In an assessment of how the vaccination programme could unfold, Professor Hill said: “I’d be very surprised if this thing [the pandemic] isn't very clearly on the way down by late spring, at least in this country ... we will get to the stage where there is herd immunity through vaccination.”
A vaccine that works is seen as a game-changer in the battle against Covid-19, which has killed more than 1.15 million people, hammered the global economy and shuttered normal life across the world.