The Moderna coronavirus vaccine has been approved for use in the UK.
It is the third jab authorised for use in the UK, joining vaccines made by Pfizer and AstraZeneca.
The Government has ordered 17 million doses of the Moderna jab, but supplies will not delivered until the spring.
Health Secretary Matt Hancock said: “This is further great news and another weapon in our arsenal to tame this awful disease.
“We have already vaccinated nearly 1.5 million people across the UK and Moderna’s vaccine will allow us to accelerate our vaccination programme even further once doses become available from the spring.
“While we immunise those most at risk from Covid, I urge everyone to continue following the rules to keep cases low to protect our loved ones.”
US firm Moderna has said its trial results indicate the jab is generally well tolerated with no serious safety concerns and trials of the vaccine suggest it is 94% effective against Covid-19.
The government had already signed a deal for seven million doses of the Moderna vaccine for the UK, but on announcement of its approval it was revealed that number had been increased by 10 million.
That is enough for around 8.5 million people, who will each receive two doses of the vaccine.
The Moderna vaccine has bee approved for use in the US and works in a very similar way to the jab from Pfizer/BioNTech.
Coronavirus is studded with “spike proteins” that it uses to enter human cells. Covid-19 vaccines target this spike protein.
The Moderna and Pfizer vaccines use synthetic messenger RNA (mRNA), a genetic material that contains information about the spike protein.
The vaccines provide the body with instructions to produce a small amount of this protein which, once detected by the immune system, leads to a protective antibody response.
Moderna’s vaccine does not require the same ultracold storage as Pfizer’s and can remain stable at normal fridge temperature for 30 days.