UPDATE 1-Britain on track for spring vaccine roll-out after Oxford results, researcher says

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LONDON, Nov 23 (Reuters) - Britain is on track to make COVID-19 vaccines widely available by next spring after the shot developed by Oxford University and AstraZeneca was up to 90% effective in trials, the head of the university's Jenner Institute said on Monday.

The encouraging late-stage trial results were the third published among the seven vaccine candidates Britain has ordered, following on from Pfizer/BioNTech and Moderna earlier this month.

Britain has secured 100 million doses of the AstraZeneca shot, 40 million of the Pfizer vaccine and 5 million of Moderna's candidate.

"I think we are on track for the timeline ... to start getting this vaccine rolled out from December," Adrian Hill, director of Oxford University's Jenner Institute that developed the vaccine, told Reuters.

He said high-risk groups would receive the vaccine before it was rolled out to everyone in spring.

"I think that could be done. It's going to be an enormous effort ... hopefully there will be vaccine available for all adults, but that's likely to be springtime rather than in January," Hill said.

An AstraZeneca executive earlier said there would be enough drug substance for 20 million vaccine doses in Britain by the end of the year, with 4 million doses ready for use.

The vaccine is administered in two shots, so more people could be inoculated if the initial shot ends up being a half dose, the regimen that has proved more effective in trials.

Britain expects 10 million doses of the Pfizer vaccine this year, but its cold-storage requirements pose logistical challenges, while Britain won't even receive any Moderna vaccines until next spring.

Oxford has said it aimed to make a COVID-19 vaccine that would be widely available around the world, helped by AstraZeneca's manufacturing and distribution capacity, while using a technology that avoids onerous storage requirements.

"We are going to be probably close to getting to that 3 billion dose target next year with just our vaccine," Hill said. (Reporting by Alistair Smout; Additional reporting by Kate Kelland; Editing by David Clarke)