Chelsea midfielder N'Golo Kante has tested positive for coronavirus and will miss Wednesday's Champions League tie with Juventus.
He will not feature against Southampton in the Premier League on Saturday and could also miss France's Nations League game with Belgium on 7 October.
Blues boss Thomas Tuchel said he did not know how many of his players are vaccinated against Covid-19.
"We are a reflection of society, the players are adults and they have a free choice," Tuchel told a news conference on Tuesday.
"We should accept it. This is more or less all I can say.