Britain has secured 5 million doses of an experimental Covid-19 vaccine developed by Moderna Inc after it reported positive trial results, health minister Matt Hancock said 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% 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 90% effective, and 100 million doses of an AstraZeneca/Oxford candidate expected to report late-stage results in coming weeks.
Earlier, Prime Minister Boris Johnson's spokesman said the government had prioritised deals with vaccine developers who could provide early supply to Britain and have advanced manufacturing supply chains in place.
Asked if he regretted not being able to buy more of the Moderna vaccine, Hancock said Britain expected to have other vaccines sooner.
"The Moderna vaccine doesn't come on stream until the spring," Hancock said. "I'm just really pleased that we've got those early vaccines that will be available early, and we've already got the orders of those in."
Britain expects to take delivery of the Pfizer vaccine before the Moderna shot becomes available, as well as AstraZeneca's candidate if it proves to be effective.
Deputy Chief Medical Officer Jonathan Van Tam said data from late-stage trials of the AstraZeneca/Oxford vaccine had not been reviewed, so it was still unknown if it works.
But he added that trial results from both the Pfizer and partner BioNTech vaccine and Moderna's augured well for other candidates that target the coronavirus' spike protein.
"This really does begin to show us that the spike protein is a completely plausible and effective target for vaccines to be working against," Van Tam said.
"We're feeling in a happier place than we were. But do we know the (Oxford/AstraZeneca) data? No we don't."