Video report from ITV News Royal Editor Chris Ship
The Queen has made an unusually direct intervention in the nationwide drive to vaccinate the adult population.
She has urged people who are reluctant to have the Covid-19 vaccine to think of others "rather than themselves".
It's significant move from the Queen who, at age 94, had the vaccine herself in January.
She said it "didn't hurt at all".
She was taking part in a video call with those in charge of the NHS vaccination programme in all four nations of the UK.
And when they spoke about the take-up of the vaccine, the Queen referred to those who have so far refused to have it.
She said: "It is obviously difficult for people if they've never had a vaccine. But they ought to think about other people rather than themselves."
It's very unusual for the Queen to be quite so direct and suggests she has concerns about the potential impact on communities if significant numbers of people don't the vaccine.
The Queen also chatted about how her own vaccine, which both she and the Duke of Edinburgh, 99, had administered at Windsor Castle.
"Once you've had the vaccine you have a feeling that you're protected", she said. "Which I think is very important. And as far as I could make it our it was quite harmless. It was very quick."
Given Buckingham Palace were initially reluctant to say when or if the Queen had been given the vaccine, it's a remarkable change from a Monarch who usually considers her own medical details a very private matter.
The Queen tells NHS leaders the vaccine was quite "harmless":
The Queen said the national fight against coronavirus reminded her of the war years when everyone pulled together.
"Having lived in the war, it's really much like that - when everybody had the same idea. And I think this has rather inspired that hasn't it?"
The Head of Scotland's vaccine programme, Derek Grieve, replied saying: "If I could bottle this community sprit and use it, not just for the vaccine programme but for other things, the job would be done."
"Wouldn't it be nice!" the Queen joked.
Chris Ship discusses the context of the Queen's message with presenter Tom Bradby
She spoke about the coronavirus as being "a bit like a plague" and that "it is a strange battle that everybody is fighting."
"I've had lots of letters from people who have been very surprised by how easy it was to get the vaccine. And the jab didn't hurt at all."
"You'll have to keep up the good work" she said to the UK's four chief vaccine officials as she commented on how "remarkable" it was that they have vaccinated more than 18 million people.
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