Ten people have tested positive for coronavirus in the latest round of testing conducted by the Premier League - the highest number of positive tests since the season began.
A total of 1,595 players and club staff were tested for Covid-19 between 21 and 27 September.
Those who have tested positive - who have not been identified - will now isolate for 10 days.
The Premier League carries out weekly testing of staff at all 20 clubs.
Last week West Ham confirmed that manager David Moyes and players Issa Diop and Josh Cullen were self-isolating after testing positive for the virus.
The 2020-21 season started on 12 September after the coronavirus pandemic caused a delay to the completion of the previous campaign.