The Oxford vaccine should have a “huge impact” on the spread of coronavirus, a chief investigator has said, but its impact on Covid variants remains unclear.
New results suggest the jab may reduce Covid transmission by up to 67 per cent, but the data was drawn before concerning new mutations emerged, Dr Andrew Pollard explained.
However, the Oxford/AstraZeneca trial’s chief investigator said researchers expect the jab to show “good protection against the Kent variant that has been circulating over the last few months here in the UK”.
“We’re looking at that at the moment, we should have some information to make public very soon,” Dr Pollard added.
The Oxford expert explained that new mutations of the virus that have been found in the UK, South Africa, Brazil and other countries show the virus is “trying to escape from human immunity – whether it’s from vaccines or from infection.”
But, he added, once natural immunity and the effect of mass-vaccinations spread across the country, Covid-19 will hopefully become “like other coronaviruses that are around us all the time, which cause colds and mild infections".
“They know their whole raison d’etre is to be able to transmit between people," he said. “But we will have built up enough immunity to prevent the other severe disease that we’ve been seeing over the last year.”
Pointing to the results published on Tuesday, Dr Pollard said the Oxford-AstraZeneca vaccine was not only more than 80 per cent effective at preventing illness, but it could also cut the spread of disease by up to two-thirds, meaning the jab “should have a huge impact on transmission”.
Oxford University researchers found that the first dose of the jab offers protection of 76 per cent for up to three months and may reduce transmission by 67 per cent – with efficacy rising to 82.4 per cent after the second dose 12 weeks later.
Before the study, which is due to be published in the Lancet journal, little was known about how effective the Covid-19 vaccines were at preventing transmission of the disease.
The findings indicate that those who have been vaccinated are not only protected from the disease, but that they are not likely to pass on the virus to anyone.
It also suggests the vaccine eliminates severe illness, as none of those in the study were admitted to hospital with coronavirus.
Dr Pollard also stressed that the vaccine showed good results among all age groups, refuting unsubstantiated claims by French president Emmanuel Macron that it was “quasi-ineffective” among the over-65s.
He said: “We have good immune responses in older adults very similar to younger adults, the protection that we do see is in exactly the same direction and of a similar magnitude to younger adults.
“I think we’re confident that we’re going to see good protection in all age groups, just as global regulators haven taken that view.”
He added that researchers were examining data on those who still had positive tests after getting the vaccine, as he warned “the virus is absolutely trying to find ways of continuing to transmit.”
“There’s two questions that need to be asked,” Dr Pollard told BBC Radio 4’s Today Programme.
“One is how much virus are they shedding and the other is for how long. We’re looking at that and we should have an answer to that really important question very soon.”
Coronavirus: Celebrities who have been vaccinated
Meanwhile, the trial’s promising findings have been celebrated by ministers and scientists alike.
Matt Hancock said the “absolutely suberb results” were proof that vaccines will “help us all to get out of this pandemic”.
The Health Secretary told BBC Breakfast on Wednesday morning: “The new information that we’ve got is that (the Oxford/AstraZeneca vaccine) also reduces transmission.
“We know from the earlier trials that the vaccines are safe and effective at protecting the individual.
“We now know that the Oxford vaccine also reduces transmission and that will help us all to get out of this pandemic, frankly, which is why it is such good news that we should welcome.”
Elsewhere, Professor Adam Finn, from the Joint Committee for Vaccination and Immunisation (JCVI), hailed the study’s conclusions as “very, very good news” but warned that jabs were still not a “silver bullet” against Covid-19.
He told Times Radio: “I think it points to the fact that all of these vaccines to some extent will be able to reduce transmission.”
Asked if the new strains show signs of being vaccine-resistant, he said: “Yes, they do, and that’s something that I guess we’ve expected all along.
“So it is going to be a game of catch-up going forward; the vaccines will continue to work, but, as virus mutates, they will work less well, and we’ll have to adjust them to bring them back up to top-level protection.
“But that’s what we do with flu all the time. It’s not something that’s that alarming or unexpected really, but it is a reality.
“There isn’t a silver bullet, we’re not going to solve this problem overnight, it’s going to take time.”