The Queen has urged the public to "think about other people" and get a Covid jab when they are offered one.
The monarch, 94, and the Duke of Edinburgh, 99, received their first doses of the vaccine in January.
In a video call with health leaders delivering the Covid vaccine across the UK, the Queen was asked about her experience of having the jab.
She smiled as she replied: "Well, as far as I can make out it was quite harmless.
"It was very quick, and I've had lots of letters from people who've been very surprised by how easy it was to get the vaccine."
The Queen, who rarely talks about her own health, added: "It didn't hurt at all."
The monarch said she understood getting a jab could be a "difficult" experience for some people but urged everyone to "think about other people rather than themselves".
It comes after UK vaccines minister Nadhim Zahawi said figures suggested 11-15% of people were vaccine-hesitant, with data skewed toward some black and ethnic minority communities.
Some studies have also found disparities between poorer and wealthier areas.
Dr Emily Lawson, who is leading the vaccine deployment programme for the NHS in England, said the Queen's comments about her vaccine experience were an "incredibly important vote of confidence in the programme".
"We just want to make sure we create the conditions where everybody feels able to take up the offer of a vaccination when they're called," she said.
"And Her Majesty offering her view on that is a huge boost to our confidence and I hope to confidence more broadly in the programme."
The Queen also said the speed of the UK's vaccination rollout had been "remarkable" so far.
Speaking to the four officials overseeing the programme in England, Scotland, Wales and Northern Ireland, she added: "Keep up the good work."
During the video call, which was held on Tuesday, the monarch likened the pandemic to a "plague" that has swept across the globe.
After Derek Grieve, head of the Scottish government's vaccine rollout, told the head of state he would like to "bottle" the community spirit he had witnessed during the epidemic, she said it felt "very much like" the wartime spirit she experienced.
Meanwhile, the Countess of Wessex has begun volunteering at a vaccination centre in south-west London.
Sophie, who is a St John Ambulance care volunteer, completed the required training to help provide reassurance and information to vaccine recipients.
St John Ambulance said it was "delighted" to welcome the countess to its team of more than 10,000 trained volunteers in vaccine centres across England.
More than 18 million people have had a first vaccine dose - equivalent to one in three adults in the UK.
The vaccine rollout has entered its next phase, after everyone in the top four priority groups was offered a jab. Many areas are now offering vaccine appointments to over-60s, adult carers of disabled people and younger adults in care homes.
Some 600,000 people out of 1.7 million added to the shielding list last week are now being invited to book a slot for a vaccine, NHS England said, while the remainder have already had their jabs as part of the first phase of the vaccination programme.
The Prince of Wales and Duchess of Cornwall have both received their first doses of the vaccine, with Camilla saying she "leapt for joy" after getting her jab.
And the Duke of Cambridge said at a vaccine centre in Norfolk on Monday that he would be at the "front of the queue" for a vaccine to help to reassure people of its safety, but that he would "wait my turn".
During his visit William also said his grandfather, Prince Philip, was "OK" after being admitted to hospital last week.
The Duke of Edinburgh remains at King Edward VII's Hospital in central London where he is being treated for an infection.