Health Secretary Matt Hancock has said, the NHS is ready to start providing the new coronavirus vaccine "as fast as safely possible", and that it is "absolutely a possibility" that it could be available by Christmas, expecting a mas roll-out early next year.

On Monday, early results from the world's first effective coronavirus vaccine showed it could prevent more than 90% of people from getting Covid.

The vaccine has been developed by pharmaceutical companies Pfizer and BioNTech and is one of 11 vaccines that are currently in the final stages of testing. The companies now plan to apply for emergency approval to use the vaccine by the end of November - and a limited number of people may get the vaccine this year.

The UK has already ordered 40 million doses - enough to vaccinate up to 20 million people as each person will need two doses for it to work effectively. But Boris Johnson has warned people not to "rely on this news as a solution" as it is still "very, very early days".

Older care home residents and care home staff are at the top of a list from government scientific advisers of who would get immunised first, followed by health workers. Mr Hancock said NHS staff would go into care homes to vaccinate residents, as well as setting up vaccination venues. Children would not be vaccinated, he said.

The vaccine will not be released for use until it passes final safety tests and gets the go-ahead from the Medicines and Healthcare products Regulatory Agency. The safety of the Pfizer vaccine has still to be proved, before it gets regulatory approval. Then there are issues of who gets it and how best to use it.  This will depend on some of the scientific questions that remain: whether the vaccine is able to stop transmission rather than just prevent disease, how long immunity lasts and whether it works with older people. 

The answers should emerge as the vaccine starts being rolled out. A limited number of people may get the Pfizer vaccine this year.