The announcement comes just a day after GP-led vaccination sites in England began to roll out the first doses of the Oxford/Astra Zeneca vaccine this week.
The Pfizer/BioNTech vaccine became the first to be authorised for use in the UK on 2 December - and prime minister Boris Johnson said on 7 January that a total of 1.5m people across the UK have now received at least one dose of vaccine.
The government announced today that it has ordered an extra 10m doses of the Moderna vaccine, which is 94% effective in preventing disease, on top of a previous order of 7m doses.
Supplies of the Moderna vaccine will start to arrive in the UK from spring this year - by which time the government hopes to have delivered millions of doses of the two other approved products to patients and health and care staff.
Health and social care secretary Matt Hancock said: 'We have already vaccinated nearly 1.5m 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.'
Deputy CMO for England Professor Jonathan Van-Tam said: 'The highly effective Moderna vaccine is another impressive success for science and is another testament to the hard work of researchers and selfless clinical trial volunteers.
'This vaccine will save lives once doses become available, but it is crucial we all continue to follow the rules to protect each other until enough people have been protected.'
The UK government has ordered 367m doses of seven vaccines either approved or in development:
- BioNTech/Pfizer - 40m doses.
- Oxford/AstraZeneca - 100m doses.
- Moderna - 17m doses.
- GlaxoSmithKline and Sanofi Pasteur - 60m doses.
- Novavax - 60m doses.
- Janssen - 30m doses.
- Valneva - 60m doses.
GPonline reported today that the government has promised to have 1,000 GP-led vaccination sites up and running by 15 January. It promised on 5 December that this number would be in place 'shortly' - but as of 5 January the total number in operation was 784.
GPs have called for the rollout of COVID-19 vaccination to be sped up - raising concerns over distribution of vaccine supply and the rollout of additional vaccination sites.