Sunderland have informed the English Football League they will not be able to fulfil their next three matches after the club's Covid-19 outbreak.
The trip to Shrewsbury Town (19 December) and home matches with Blackpool (22 December) and Hull City (26 December) have all been postponed.
Sunderland made the decision to go ahead with that game but the club were "unclear" on potential EFL sanctions.
After one senior player tested positive for coronavirus on Monday, a further four cases have now been confirmed among players and staff at the club's Academy of Light training base.