Dialysis patient Brian Pinker, 82, has become the first person to receive the Oxford-AstraZeneca Covid-19 vaccine.
The retired maintenance manager got the jab at 7:30 GMT from nurse Sam Foster at Oxford’s Churchill Hospital.
More than half a million doses of the vaccine are ready for use on Monday.
Health Secretary Matt Hancock said it was a “pivotal moment” in the UK’s fight against the virus, as vaccines will help curb infections and then allow restrictions to be lifted.
But Prime Minister Boris Johnson has said regional restrictions in England are “probably about to get tougher” as the UK struggles to control a new, fast-spreading variant of the virus.
On Sunday more than 50,000 new confirmed Covid cases were recorded in the UK for the sixth day running, prompting Labour to call for a third national lockdown in England.
Northern Ireland and Wales currently have their own lockdowns in place, while Scottish cabinet ministers will meet later to consider further measures.
The rollout comes as rows continue over whether pupils should return to school with the current high levels of Covid infection.
Six hospital trusts – in Oxford, London, Sussex, Lancashire and Warwickshire – are administering the Oxford-AstraZeneca jab on Monday, with 530,000 doses ready for use.
Most other available doses will be sent to hundreds of GP-led services and care homes across the UK later in the week, according to the Department of Health and Social Care.
Mr Pinker, who has been having dialysis for kidney disease at the Churchill Hospital for a number of years, said he was “really proud” the vaccine was developed in Oxford.
“The nurses, doctors and staff today have all been brilliant and I can now really look forward to celebrating my 48th wedding anniversary with my wife Shirley later this year,” he said.
Music teacher and father-of-three Trevor Cowlett, 88, and Prof Andrew Pollard, a paediatrician working at the Oxford University Hospitals NHS Foundation Trust, were also among the first to be vaccinated.
Chief nurse Ms Foster, who administered the first dose, told the BBC it was a “huge privilege”, saying: “Every single patient that we have vaccinated over the last couple of weeks have got their own personal stories to the difference it’s going to make, so it is no different this morning.”