Queen Elizabeth II revealed that COVID-19 left her "very tired and exhausted" after she caught the virus earlier this year, The BBC reported on Sunday.
The 95-year-old monarch was taking part in a virtual hospital visit last week when she described her experience to a former virus patient, whose father and brother died with the illness.
Buckingham Palace said in February that the Queen had coronavirus and was suffering "mild cold-like symptoms" at the time.
During her video call to the hospital, the Queen said: "It [COVID] does leave one very tired and exhausted, doesn't it?"
Speaking to former COVID patient Asef Hussain and his wife Shamina, she added, "This horrible pandemic. It's not a nice result."
The call to the Royal London Hospital marked the official opening of its Queen Elizabeth Unit.
The Queen’s COVID diagnosis followed reports that she had some health problems. In October, Buckingham Palace revealed that she had spent one night in hospital for “preliminary investigations” before returning to Windsor Castle the next day.
It was later announced that the Queen would not attend the COP26 UN climate conference in Glasgow, though she spoke at the conference via video.