Study: 3rd AstraZeneca shot gives strong immunity

The British government says it's looking at plans for an autumn campaign for coronavirus vaccine booster shots.

To date three-fifths of adults in the UK have already had both doses of a COVID vaccine.

Now, an Oxford University study has found that a third dose of the Oxford-AstraZeneca vaccine produces a strong immune response... making it a possible candidate.

But researchers added there was not yet evidence that such shots were needed, especially given shortages in some other countries.

Teresa Lambe is an associate professor at Oxford University.

“The data that is coming out from the real world effectiveness is showing these vaccines are having a huge impact against hospitalization. And there are so many countries around the world that haven’t even had one dose yet so that at the moment I think those doses should go to countries where they haven’t even had one dose. That scenario, that picture may change as we had towards winter and perhaps we may see that this vaccine's effectiveness does need a boost but at the moment I don’t think we’re seeing that evidence.”

The Oxford University study found that a third dose of the vaccine increases antibody and T-cell immune responses, while the second dose can be delayed up to 45 weeks and also lead to an enhanced immune response.

Studies had previously shown that the shot has higher efficacy when the second dose is delayed to 12 weeks instead of four weeks.

Monday's research may also help alleviate concerns that vaccines may lose their potency if annual inoculations are needed.

“What we are seeing when we give a third dose of the Oxford Astrazeneca vaccine is that you augment the antibody immunity, so you push the antibodies up higher than what you see even after a second dose. So there had been some concerns that we would not be able to use this vaccine in a booster vaccination regime, and that’s certainly not what the data is suggesting.”

At the weekend, Oxford launched another trial this time using a modified version of its COVID-19 vaccine to better target the Beta variant that was first identified in South Africa.

It is the variant which most worries vaccinologists for its immune-escaping potential.

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