The palace announced Sunday that the 95-year-old monarch had contracted the virus.
"As Her Majesty is still experiencing mild cold-like symptoms she has decided not to undertake her planned virtual engagements today, but will continue with light duties," the palace said.
Light duties likely refer to her head of state responsibilities such as reading and answering documents and letters, which she receives daily in her famous red despatch boxes.
A source close to the palace told CNN that the Queen's further engagements over the coming week will be decided upon nearer the time.
Concern for the Queen's health has been renewed given her advanced age and health issues late last year. However, she has continued to work since Sunday despite testing positive for the coronavirus, issuing a message of condolence to the people of Brazil over flooding in the country on Monday.
The Queen's diagnosis is the latest Covid case to hit the royal household. Her eldest son and heir to the British throne, Prince Charles, contracted the virus for a second time on February 10, and had seen his mother "recently." Days later, his wife, Camilla, also tested positive.
Additionally, a royal source told CNN Sunday that there had recently been "a number of cases ... diagnosed in the Windsor Castle team."
UK media have reported that the Queen is fully vaccinated. Buckingham Palace previously confirmed both the monarch and her late husband, Prince Philip, had received their first doses of a Covid-19 vaccine in January 2021. The palace has declined to reveal any information regarding subsequent vaccinations, citing medical privacy.
The Queen -- who reached the milestone of 70 years as British monarch on February 6 -- had only recently resumed in-person engagements after taking a step back on advice from doctors to rest following an overnight hospital stay in October for an undisclosed reason.
She has used a walking stick at several engagements in recent months and referenced her mobility at an event last week. While holding an audience with two military secretaries in the Oak Room at Windsor Castle, she quipped: "Well, as you can see, I can't move," while gesturing to her leg. A royal source told CNN at the time that she was believed to have been feeling slightly stiff rather than injured or unwell.
She also has made plans to appear at a number of major engagements next month: a diplomatic reception at Windsor Castle on March 2, the annual Commonwealth Service at Westminster Abbey on March 14; and a service of thanksgiving for Prince Philip at the same venue on March 29.
Nationwide celebrations for her Platinum Jubilee are set to take place in June.