Watford have confirmed a player and two members of staff have tested positive for coronavirus after players and staff from Premier League clubs were tested.
Six of the 748 tests carried out came back positive so half of the six were at Watford, while Burnley assistant manager Ian Woan was the first case to be made public.
Burnley say Woan is asymptomatic, but the former Nottingham Forest winger will self-isolate for the required seven days.
19 clubs were tested on Sunday and Monday while Norwich City did their tests on Tuesday.
Before the news about Watford's positive tests emerged, captain Troy Deeney said he would not return to training due to concerns over BAME players and his own son's welfare
"We're due back in this week. I've said I'm not going in. It only takes one person to get infected within the group and I don't want to be bringing that home.
"My son is only five months old. He had breathing difficulties, so I don't want to come home to put him in more danger."
There were 92 games remaining when the Premier League was suspended on March 13th because of the pandemic.
The season moved one step closer to resuming in June when clubs agreed to stage one of the return-to-training protocols at Monday's "Project Restart" meeting.
Liverpool and Manchester United were among the clubs to start training in small groups on Wednesday.
A session can last no longer than 75 minutes and have no more than five players in a group five, while social distancing measures will also be in place.
The Bundesliga became the first major European football league to restart when it resumed last Saturday, meaning it took almost five weeks from starting non-contact training to playing matches.
Every club in Germany's top flight was in quarantine, going from a hotel to their training ground for the week leading up to the restart.