Buckingham Palace says the Queen has tested positive for Covid.
The palace said the monarch is experiencing “mild cold-like symptoms” but expects to continue “light duties” at Windsor over the coming week.
The palace said in a statement “She will continue to receive medical attention and will follow all the appropriate guidelines”.
The Queen, 95 years old, had been in contact with her eldest son and heir, the Prince of Wales, who tested positive last week.
The announcement comes weeks after the Queen became the UK’s longest reigning monarch, reaching her Platinum Jubilee of 70 years on 6 February.
She carried out her first major public engagement for more than three months on the eve of her Jubilee, meeting charity workers at Sandringham House.