Covid-19: Vaccines protect in three ways
Prof Chris Whitty has set out three ways in which the Covid-19 vaccine could protect people.
He said it would protect the person vaccinated to a degree, reduce the risk to people they come into contact with and help reduce the amount of virus circulating in the population as a whole.
Turning to the number of people who have received a vaccine, Prof Whitty said it is "steadily increasing" in all four nations in the UK.