Britain's Queen Elizabeth II, who turns 96 on 21 April, has spoken of serious fatigue after she contracted COVID-19 in February despite aides downplaying her illness.
At the time, Buckingham Palace said the vaccinated monarch had "mild, cold-like symptoms".
But she was forced to cancel a series of appointments with foreign diplomats, at the start of her record-breaking 70th year on the throne.
Queen Elizabeth II speaks to hospital staff during a video link call and virtual visit to the Royal London Hospital on Wednesday to mark the official opening of the hospital's Queen Elizabeth Unit. Source: AAP / Ralph Hodgson / PA
Speaking to one former COVID-19 patient who required ventilation, the Queen said about the virus: "It does leave one very tired and exhausted, doesn't it?
"This horrible pandemic. It's not a nice result," she said, according to footage released by the palace on Sunday.
The unit at the Royal London Hospital was built in record time to cope with an influx of COVID-19 sufferers.
The construction team hailed the "Dunkirk spirit" that inspired them, referring to the World War II retreat of British and allied forces from northern France, in the face of a Nazi onslaught.
"Thank goodness it still exists," the Queen replied.
"It is very interesting, isn't it, when there is some very vital thing, how everybody works together and pulls together – marvellous, isn't it?"
Fears for the Queen's health have lingered since she had an unscheduled overnight stay in hospital last October, which was only revealed by the palace later.
Her public appearances have become rarer since, and she has complained of mobility problems, as her 96th birthday approaches on 21 April.
She is to miss a religious service on Maundy Thursday this week and will be represented by her eldest son and heir, Prince Charles.
The service marks the start of Easter weekend and is normally a fixture in her calendar.