Chelsea may have to do without star midfielder N'Golo Kante for the rest of this season.
Kante has still not resumed training with the rest of the team.
He has been at the club's Cobham base, but only for individual workouts.
Kante has a family history of heart problems, and had a health scare two years ago when he collapsed during a training session.
ESPN says Chelsea are preparing for the league games without Kante, unless there is a chance in the situation.
The World Cup winner did not take part in an intra-squad game this past weekend.
The player is not only concerned about himself, but potentially spreading the virus to family members.