However, Buckingham Palace has confirmed that Her Majesty is in good health.
The televised event will be shown at 8 p.m. on Sunday.
Speaking from Buckingham Palace and against a backdrop of a view of the crowds of mourners outside, the Queen, dressed in black, said she was speaking from her heart as both the nation's Queen and as a grandmother. "A time of disruption in the life of our country: a disruption that has brought grief to some, financial difficulties to many, and enormous changes to the lives of us all".
She will also address how the nation has responded, saying: "I hope in the years to come everyone will be able to take pride in how they responded to this challenge".
"That the attributes of self-discipline, of quiet, good-humoured resolve and of fellow feeling still characterise this country".
With the weekend predicted to be the warmest of the year so far, the Queen will also thank those who are following the official guidance to stay at home to protect the vulnerable. That came a decade after the preceding broadcast which followed the death of her mother, the Queen Mother, in 2002 when she thanked Britons for their messages of condolence.
In order to ensure any risk to the Queen herself was mitigated, it was filmed in a big room to ensure a safe distance between her and the cameraman, who was wearing personal protective equipment and was the only other person present.
"The Queen will demonstrate, as she has done on so many occasions, why she is one of our greatest monarchs in history", a royal source added.
What time is the Queen's coronavirus speech?
The initial appeal was for 250,000, while business and industry have been mobilised in a way unseen since World War II.
Her eldest son and heir Prince Charles, 71, has been in self-isolation on her sprawling Balmoral estate in northeast Scotland after developing mild symptoms of COVID-19. The facility was built in nine days by members of the armed forces from an empty conference centre at the ExCeL arena.
The Queen's address will come less than a week after the Prince of Wales came out of self-isolation, following his diagnosis of coronavirus.