The monarch and her 99-year-old husband Prince Philip - who is in hospital receiving treatment for a non-COVID infection - received their vaccines from a household doctor at Windsor Castle, with their age putting them in the priority group for England's coronavirus vaccine rollout.

"It was very quick, and I've had lots of letters from people who have been very surprised by how easy it was to get the vaccine," the Queen said in a video call on Tuesday with health officials overseeing the inoculations' delivery across the United Kingdom.

"And the jab - it didn't hurt at all," she said in remarks released by Buckingham Palace.

More than 18.6 million Britons have already received their first vaccine injection, and celebrities including Elton John and Michael Caine have joined campaigns encouraging people to take up offers to have the shot.

Other members of the royal family, including Prince Charles and Prince William, have been visiting vaccination centres over the last fortnight to thank staff and volunteers for their work.

It comes, though, amid concern over the health of Prince Philip, the Duke of Edinburgh, who was admitted to a London hospital last week and has since spent nine nights there receiving medical attention for an unspecified infection.

The palace have said Philip, who turns 100 in June, was comfortable and responding to treatment, but likely to remain in hospital for several days.

On Tuesday, the Duke and Prince Edward said he was "a lot better", and the day before William said his grandfather was "OK".

Australian Associated Press