The head of state felt well enough to speak to foreign diplomats after postponing a number of similar engagements last week.
The monarch tested positive for the virus on February 20 and Buckingham Palace said at the time she was experiencing “mild cold like symptoms”.
On Tuesday she received His Excellency Mr Carles Jordana Madero, who presented the Letters of Recall of his predecessor and his own Letters of Credence as ambassador from the Principality of Andorra to the Court of St James’s.
She also received His Excellency Mr Kedella Younous Hamidi, who presented his Letters of Credence as ambassador from the Republic of Chad to the Court of St James’s.
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During the two audiences the Queen wore a green dress with a large brooch and her trademark pearls.
It comes after a diplomatic reception the monarch was due to host at Windsor Castle on Wednesday was also postponed.
The Queen was due to meet hundreds of members of the Diplomatic Corps but Buckingham Palace said on Saturday she had accepted the Foreign Secretary’s advice to delay the event. It is understood the decision was made because of Russia’s invasion of Ukraine.
She has a string of high-profile events coming up that she is due to attend, including the Commonwealth Service at Westminster Abbey on March 14, and then the Duke of Edinburgh’s memorial service, also at the Abbey, on March 29.
The nation’s longest reigning monarch, who is believed to have been triple vaccinated, recently spent more than three months resting, on doctors’ orders.