NEW data shows the Oxford/AstraZeneca vaccine is 100 per cent effective at preventing severe disease in patients.

The US-led study also found it is 79 per cent effective at preventing people catching Covid-19.

Some 32,449 people across all age groups took part in the phase three trial in the US, Chile and Peru, with a total of 141 cases of symptomatic Covid-19 reported.

The results showed among people aged 65 and over, there was 80 per cent protection against developing Covid-19.

The degree of effectiveness against symptomatic Covid-19 was even higher than observed in the Oxford-led clinical trials.

An independent data safety monitoring board (DSMB) also identified no safety concerns relating to the vaccine.

It conducted a specific review of thrombotic events, as well as cerebral venous sinus thrombosis (CVST) – the specific type of brain blood clot that has been troubling Europe.

The DSMB found no increased risk of thrombosis among the 21,583 participants receiving at least one dose of the vaccine.

The specific search for CVST found no cases in this trial.

Andrew Pollard, professor of paediatric infection and immunity, and lead investigator of the Oxford University trial of the vaccine, said: “These results are great news as they show the remarkable efficacy of the vaccine in a new population and are consistent with the results from Oxford-led trials.

“We can expect strong impact against Covid-19 across all ages and for people of all different backgrounds from widespread us of the vaccine."

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AstraZeneca will now submit data to the US Food and Drug Administration (FDA) and seek emergency approval for use.

The US had been waiting for the latest results before considering it.

The US trial saw two doses given four weeks apart, whereas previous trials have shown that an extended interval of up to 12 weeks demonstrated greater efficacy.

AstraZeneca said leaving an interval longer than four weeks – as is happening in the UK – can increase efficacy and “accelerates the number of people who can receive their first dose”.

As part of an agreement with Oxford, AstraZeneca is supplying the vaccine on a not-for-profit basis for the duration of the pandemic and in perpetuity for low and middle-income countries.