Chelsea midfielder N'Golo Kante has tested positive for Covid-19 and entered self-isolation.
France's World Cup winner will miss Chelsea's Champions League clash at Juventus on Wednesday night.
Chelsea boss Thomas Tuchel admitted he does not know the percentage of the Blues squad that have been vaccinated, but the German coach revealed he has received the vaccination himself.
Tuchel insisted players must retain personal choice over Covid vaccines, at the same time as hoping for a quick recovery for Kante.
"N'Golo unfortunately tested positive, and needs to have time and follow the government protocols," said Tuchel.
"He was not in training today and of course was not with the group.
"I don't know the percentage of players vaccinated actually. It's not even that I don't want to tell you but I simply don't know it.
"And we are also only a reflection of society, the players are adults and it's free choice if they want to get vaccinated or not. And I think we should accept it."
"Every time someone gets it here from us or from our group, it makes us very aware the Covid situation is not over.
"I hope that it gets as less as possible but I clearly don't have a solution. I can make the decision for myself, and everybody else needs to reflect about it and take a risk or not.
"I think it's a serious question and vaccination seems to be a proper protection. I am vaccinated, I took the decision for myself.
"But I don't really see myself in a position to speak out proper recommendations, I think that would go too far."