Mako Vunipola has withdrawn from the England rugby squad to undergo a period of self-isolation amid fears over the spread of the coronavirus.
The Saracens prop was due to train with head coach Eddie Jones' extended 34-man training squad at their camp in Bagshot this week but he has been advised by doctors to self-isolate at home.
Vunipola missed England's 24-12 Six Nations win against Ireland at Twickenham nine days ago and now looks set to miss the rest of the Championship.
An England spokesperson said: "Mako Vunipola is not in the camp on medical grounds. He is not sick but it is a precaution."
Vunipola missed the game against Ireland after he was allowed to fly back to Tonga for family reasons.
He returned to London at the weekend and while England management said he was showing no symptoms of coronavirus, he was advised to stay away from the squad as a precaution, as he had flown through Hong Kong on his way back.
It is understood that his period of self-isolation could match or even go beyond the UK government's recommendation of 14 days.
England's remaining fixtures in the Six Nations are against Wales at Twickenham this Saturday before their final game against Italy at the Stadio Olimpico on Saturday March 14.
Vunipola's absence leaves Jones with Joe Marler and Ellis Gegne as his remaining loosehead options for the Welsh clash.
England forwards coach Matt Proudfoot is confident that Marler and Gegne can continue their good run of form in the tournament.
"We were excited to have him back, he is a great presence and a very experienced player, but we have great depth in our looseheads and they have been playing well," said Proudfoot.
"We will give the guys a go who were there. Mako is a world-class player, but the guys have been doing a great job."