“I feel fine, but I am afraid I have turned Covid-19 positive again. My doctors say it is a Covid rebound, which happens in 5% to 10% of cases,” said the 71-year-old in a Facebook post.

Lee said he is still infectious although the risk is not high compared to the initial infection. He has been advised to isolate himself until he tests negative.

He first tested positive for the virus on May 22 following his visits to South Africa and Kenya and was prescribed the antiviral medication Paxlovid.

The US Centers for Disease Control and Prevention issued a health advisory in May last year about the potential for the recurrence of Covid-19.

It said a brief return of symptoms may be part of the “natural history” of the virus in some people, independent of treatment with Paxlovid and regardless of vaccination status.

A Covid rebound has been reported to occur between two and eight days after initial recovery and is characterised by a recurrence of symptoms or a new positive viral test after having tested negative.