After a desperate, deadly year of coronavirus, the UK's vaccination programme has delivered first doses to 15 million of the oldest and most vulnerable.
Every vaccine bought for the UK has been on the assumption that just 30 million people - less than half the population - will get it.
Two COVID-19 vaccines being tested in the UK have moved on to the third phase of trials, marking a significant step forward in the development process.
An study has found that 50% of the UK's population may refuse a coronavirus vaccination if one becomes available.
Around 90% of experimental vaccines never reach the clinic because of problems in development or manufacture.