A THIRD shot of the Oxford-AstraZeneca vaccine could be an effective booster jag without the need for tweaks, new research suggests.

An Oxford University study found that giving people a third dose more than six months after their second led to a substantial rise in antibodies and increased the body’s T-cell ability to fight coronavirus, including its variants.

Professor Sir Andrew Pollard, head of the Oxford Vaccine Group, said it is not yet known whether people will need a booster shot in the autumn but the new data shows the existing vaccine could be effective.

He said real-world data from Public Health England (PHE) has already shown that two doses offer good protection against hospital admission and death from the Alpha Kent variant and the Delta variant first identified in India.

PHE analysis indicates that a single dose reduces the risk of hospitalisation from the Delta variant by 75 per cent, two doses by 92%, and symptomatic infection by 60% after two doses.

Prof Pollard said it is “difficult to say” whether a third dose could add a few more per cent, but added: “Boosters are much more about if protection gets lost over time – and we don’t know that – but if it does, could you boost? And the answer to that from these data is yes, you could.

“There’s no indication today that we need boosters, and it is something where we need to keep looking at the data and make decisions as the months go by, about whether that protection that we have is lost.”

To date just over 60% of adults in Scotland have been fully vaccinated, with two thirds receiving the AstraZeneca vaccine.

Prof Pollard said experts will “expect to see immunity start to wane over time” but it will not go back “down to zero”.

He added: “Our immune systems are a bit too clever for us to just look at those numbers... the immune system remembers that we’ve been vaccinated and so, even if we meet the virus some months later, the immune system remembers it, will kick in and make stronger immune responses again and hopefully that will protect most people from severe disease.

“So that’s why I say we just have to watch at the moment to make those decisions [on whether boosters are needed], based on the best evidence as it emerges.”

Teresa Lambe, associate professor at the Jenner Institute at Oxford, said a third dose had pushed the antibody response “up to a level that we saw at the peak of the response after the second dose”.

She added: “This is very encouraging because we’ve already demonstrated that two doses of [the vaccine] is both efficacious and effective in the real world.

“We also saw an increase in the neutralising antibodies against a number of variants, so we were able to demonstrate increased neutralising antibodies with a third dose against Alpha, Beta and Delta.”

The Beta variant is the one first identified in South Africa whose mutations had been worrying scientists due to potential vaccine escape.

Although cases have been detected across the UK it has not taken off to any significant degree, whereas the highly-transmissible Delta variant now accounts for over 90 per cent of cases.

The study, which has still to be peer-reviewed, also found that a longer delay of up to 45 weeks between the first and second dose of the Oxford/AstraZeneca vaccine leads to enhanced immune response.

Prof Pollard said the findings should come as “reassuring news to countries with lower supplies of the vaccine”.

It comes after AstraZeneca and Oxford University began new clinical trials on Sunday to test a new vaccine which has been designed with minor genetic alterations designed to tackle the Beta variant.

Prof Pollard said it was important to be prepared but said supplies for other countries should be prioritised over boosters.

He said: “When we have high levels of protection in the UK population, and no evidence of that being lost, to give third doses now while other countries have zero doses is not acceptable.

“We have to make sure that other countries are protected.”