The Duchess of Cornwall revealed she "leapt for joy" after having her COVID-19 vaccination earlier this month.
Camilla, 73, made the comments as she and the Prince of Wales spoke with patients waiting to have their injections at The Queen Elizabeth Hospital in Birmingham on Wednesday.
The couple, who made the first in-person royal appearance of 2021, witnessed the vaccine being delivered to vulnerable patients and thanked some of the 250,000 hidden heroes who have taken part in the clinical vaccination trials.
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WATCH: Prince Charles and Duchess of Cornwall thank vaccine trial volunteers and staff
Speaking with Nicki Cadwallader, 50, who had her vaccine as part of a trial for cancer patients, the Duchess said: "It's a good thing. It doesn't hurt.
"I was waiting for it to be done and they said 'it has been done'. It was painless. It was brilliant.
"It's very good when it's over as you feel more secure. Panic over."
Camilla later told vaccination trial staff: "I leapt for joy. I didn't feel anything. I'm eternally grateful for everything."
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The royal couple with Health Secretary Matt Hancock
When the heir to the throne and his wife first arrived at the hospital, they were greeted at a distance by the Health Secretary Matt Hancock and all wore face masks.
The University Hospitals Birmingham NHS Foundation Trust is believed to have treated the largest number of Covid-positive patients of any NHS Trust in the UK – more than 12,500 – with 10,000 of these discharged.
Charles, who contracted coronavirus last March, paid tribute to NHS heroes during the visit saying: "I know over the last year must have been absolutely exhausting for so many of you.
"And I know the NHS is such an enormous team and there are masses of people who are unsung and unseen heroes and heroes.
Charles and Camilla met patients and staff at the hospital
"We owe them all such an enormous debt of gratitude. So many of you particularly, the pressures are huge, it must be so difficult organising all other aspects of your lives let alone the difficulties when dealing with people who are very, very sick or those who tragically die.
"You are an amazing team, if I may say so, we are very lucky indeed to have you and I hope you continue to have increasing success in battling against this abominable virus.
"But you are winning by the sounds of it. That is a great thing. Thank you thank you for everything you do."
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