It was the second time this week that Elizabeth, 95, had cancelled virtual sessions.
However, she spoke by telephone with British Prime Minister Boris Johnson on Wednesday in what was seen as an encouraging sign of her recovery.
Queen Elizabeth tests positive for COVID-19
The monarch’s age, COVID-19 diagnosis and a health scare last year have caused worry among officials and the public.
Her positive test for the coronavirus over the weekend prompted concern and get-well wishes from across Britain’s political spectrum.
The palace said Sunday that Elizabeth, who has been fully vaccinated and had a booster shot, would continue with “light” duties at Windsor Castle.
The queen, who is the country’s longest-reigning monarch, has a series of engagements coming up as she celebrates her Platinum Jubilee, marking 70 years on the throne.
She is scheduled to host a March 2 reception which would involve meeting hundreds of diplomats at Windsor.
She is also due to attend the Commonwealth Service at Westminster Abbey on March 14, and then a March 26 memorial service, also at the Abbey, for her late husband, Prince Philip, who died last April at age 99.
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