Sir Keir Starmer has gone into self-isolation after a family member showed symptoms of coronavirus.
It means Sir Keir will not be able to speak in today's Commons debate and will have to work from home.
Shadow business secretary and former Labour leader Ed Miliband will fill-in for Sir Keir during the debate on a key amendment to the UK Internal Markets Bill .
The Prime Minister's spokesman said that he had spoken to Sir Keir and "gave him his best wishes".
The news was announced shortly after the Labour leader took part in his monthly LBC show, Call Keir. His office has contacted LBC.
A spokesman for Sir Keir said: “This morning Keir Starmer was advised to self isolate after a member of his household showed possible symptoms of the coronavirus.
"The member of his household has now had a test. In line with NHS guidelines, Keir will self-isolate while awaiting the results of the test and further advice from medical professionals.”
It is understood Sir Keir has not shown any symptoms of the virus.
It comes after Jacob Rees-Mogg had to go into self-isolation with his family after one of his children displayed symptoms of coronavirus.
Mr Rees-Mogg was absent from the Commons during business questions on Thursday morning.
The father-of-six wrote on Twitter: "One of my children was tested for Covid-19 last weekend after displaying symptoms.
"In accordance with government guidance, the household has been in self-isolation while we await the test result."
