Three Arsenal players were unable to train in the build-up to last week's defeat at Manchester City after one of them returned a positive Covid-19 test.
The Athletic reported Arsenal have refused to name the individual and he also came into close contact with two other players.
Under Premier League protocols, all three had to go into self-isolation.
The trio showed no symptoms, were tested again - this time all negative - and trained before the City game.
All three were involved in the 3-0 defeat at Etihad Stadium.