The Oxford coronavirus vaccine shows a strong immune response in adults aged 60 and 70, raising hopes that it can protect the age groups most at risk from the virus.
The researchers say the Lancet phase two results, based on 560 healthy adult volunteers, are “encouraging.”
They are also checking whether the vaccine is preventing people from developing Covid-19 in larger phase three trials.
The first results of this crucial step are expected in the coming weeks.
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Three vaccines – Pfizer-BioNTech, Sputnik and Moderna – have already reported good preliminary data from phase three trials, one of which suggests that 94% of people over 65 could be protected against Covid- 19.
The Oxford data comes from an earlier phase, which tests the safety of the vaccine and the body’s response to it, but in the long term, this vaccine is likely to be easier to deploy because it doesn’t does not need to be stored at very cold temperatures.
The UK government has ordered more doses of the Oxford vaccine, manufactured by AstraZeneca, than any other vaccine – 100 million doses – compared to 40 million doses of the Pfizer-BioNTech vaccine and five million of the Moderna vaccine.
Professor Andrew Pollard, head of the study at the University of Oxford, told the BBC he was “absolutely delighted with the results” showing a strong immune response “even in people over 70”.
As to whether the vaccine protects people against Covid-19, he said they were “not there yet” but the data would likely be released “before Christmas”.
According to Professor Pollard, there is “no competition” with other vaccines and several others must be effective.
“We will need all of these vaccines to protect people around the world,” he adds.
The challenge in developing a vaccine against covid-19 is to get the body to defend itself against the virus, regardless of the person’s age.
Because the immune system in older people is weaker, vaccines tend not to work as well as in younger people.
The results of these Oxford University trials, published in The Lancet, suggest that this is not a problem.
They show that adults aged 56 to 69 and over 70 have an immune response similar to that of young adults aged 18 to 55.
Protect the most vulnerable
Dr Maheshi Ramasamy, an investigator with the Oxford Vaccine Group, explains that “the next step will be to see if this translates into protection against the disease itself.”
Two weeks after the second dose, over 99% of participants had neutralizing antibody responses. They were people of all ages.
T cell response – another measure of the quality of the immune system’s response – peaks two weeks after the first dose of the vaccine, regardless of age.
“The robust antibody and T cell responses observed in the elderly in our study are encouraging,” concludes Dr Ramasamy.
“The populations most at risk for serious illness from Covid-19 include people with existing health problems and the elderly.
“We hope our vaccine will help protect some of the most vulnerable people in society, but more research is needed before we can be sure.”
The elderly are also less likely to experience side effects, which are usually mild.
And there have been no serious safety concerns with the vaccine, called ChAdOx1 nCov-2019.
The trial volunteers were divided into groups and received one or two doses of the vaccine or a dummy injection. The reaction of their immune system was evaluated on the day they received the injection, then one, two and four weeks after the two doses.
The Oxford vaccine is made from a weakened version of a cold virus (known as adenovirus) from chimpanzees, which has been modified not to develop in humans.
Work on the vaccine began in January and it was finalized in less than three months. The first human trials – the first in Europe – began in April in Oxford.
The third phase of vaccine trials, which aims to determine its effectiveness in protecting people against Covid-19, began in late August and is still ongoing.
When the data from this phase is sent to regulatory authorities, reviewed and approved, the vaccine can be used around the world.
The Oxford vaccine is expected to be easier to manufacture globally than that of Pfizer and Moderna, and the university is committed to making hundreds of millions of doses available to developing countries.
The UK’s large order for this vaccine means that if it is approved before Christmas and becomes available early next year, it would make a major difference in how quickly Covid vaccines could be given to people in the priority groups.
The announcement of the vaccine comes amid a debate in the UK over whether people will be able to see their families over Christmas time.
Professor Andrew Hayward – director of UCL’s Institute of Epidemiology and Health Care and a member of the Government’s Scientific Advisory Group for Emergencies – told the BBC family gatherings at Christmas would present “risks substantial “.
“We are on the verge of being able to protect these elderly people, whom we love, by vaccination,” he told Radio 4’s Today program.
“It would be tragic to waste this opportunity … trying to get back to normal while on vacation.”
He added: “My personal opinion is that we put too much emphasis on an almost normal Christmas.”