Six Premier League people have tested positive for COVID-19 out of 748 tests undertaken.
Players and staff were tested on Monday and the six positive tests came from three clubs.
A Premier League statement said: "The Premier League can today confirm that, on Sunday 17 May and Monday 18 May, 748 players and club staff were tested for COVID-19.
"Of these, six have tested positive from three clubs. Players or club staff who have tested positive will now self-isolate for a period of seven days.
"The Premier League is providing this aggregated information for the purposes of competition integrity and oversight.
"No specific details as to clubs or individuals will be provided by the Premier League due to legal and operational requirements."
Clubs and individuals have not been disclosed by Premier League for data protection reasons, and clubs are expected to take part in a second phase of testing later this week.
Many clubs returned to training in groups on Tuesday, while the rest will return on Wednesday after clubs unanimously voted in favour of doing so.
However, one man that seemingly won't be returning to training this week is Watford captain Troy Deeney.
"We're due back in this week, I've said I'm not going in," Deeney explained.
"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.
"My problem was in the meeting, I asked very simple questions.
"For black, Asian and mixed ethnicities, they're four times more likely to get the illness, they're twice as likely to have long lasting illnesses - is there anything extra, additional screening, heart stuff to see if people have got problems with that? No. OK, well I feel that should be addressed.
"I can't get a haircut until mid-July but I can go and get in a box with 19 people and go and jump for a header and nobody could answer the questions, not because they didn't want to, just because they don't know the information.
"So I said if you don't know the information, why would I put myself at risk?"