Buckingham Palace said on Friday that her doctors had advised Queen Elizabeth II to rest for at least two weeks.
In a statement, the palace said it had advised her to avoid official visits and only carry out “light office tasks.”
The statement added that the Queen would therefore not be able to attend a festival commemorating those who served Britain and the Commonwealth countries scheduled for November 13.
However, she said she had a “strong intention” to attend a national service of military veterans memorial the next day.
It comes just over a week after the Queen, at 95 and the world’s longest-reigning monarch, was forced to spend her first night in hospital in years at London’s private King Edward VII Hospital.
download NBC News app For breaking news and politics
The Queen stayed overnight after undergoing “preliminary investigations” for an unspecified illness unrelated to Covid-19.
Officials said Elizabeth was in good spirits after the visit, and returned to her light duties upon her return to Windsor Castle the next day.
Earlier this week, Buckingham Palace also announced that it would not attend the COP26 climate conference in Scotland due to medical advice to rest after her hospital stay.
Before visiting the hospital, she also had to cancel a trip to Northern Ireland.
In recent days, the Queen has held public engagements, including virtual audiences, to welcome the new ambassadors to Britain from South Korea and Switzerland.
The palace said it would be able to continue to retain “some virtual audiences”.
She is set to celebrate her platinum jubilee, which celebrates 70 years on the throne, next year, and she still maintains a busy schedule of royal duties, even in the months following the death of her husband, Prince Philip, who died at the age of 99 in April.