Britain has secured 5 million doses of an experimental Covid-19 vaccine developed by Moderna Inc after it reported positive trial results, Reuters quoted health minister Matt Hancock as saying on Monday, with the earliest doses expected for delivery in spring.

Interim data from a late-stage trial indicated Moderna's vaccine was 94.5 per cent effective in preventing Covid-19.

“We have today secured an initial agreement for 5 million doses of the Moderna vaccine,” Hancock said at a news conference.

Britain had previously secured supply deals for a total of 350 million vaccine doses from six different suppliers, including Pfizer Inc, whose vaccine was found to be more than 90pc effective, and 100 million doses of an AstraZeneca/Oxford candidate, expected to report late-stage results in coming weeks.