The Prince of Wales, who is self-isolating after testing positive for Covid-19, met the Queen two days ago in Windsor, a royal source says.
They say the monarch is not showing any symptoms of coronavirus.
Prince Charles tested positive on Thursday morning – it is the second time he has contracted the virus.
On Wednesday, he and his wife, the Duchess of Cornwall, met Chancellor Rishi Sunak and others at a reception in the British Museum.
Camilla tested negative for coronavirus on Thursday, Clarence House said.
Prince Charles, the 73-year-old heir to the throne, last caught the virus in March 2020 when he reported only mild symptoms.
Clarence House confirmed he was triple vaccinated, but would not give any detail on whether he was experiencing coronavirus symptoms this time.