Nine people at six Championship clubs have tested positive for Covid-19 in the latest round of testing.
Preston and Sheffield Wednesday have confirmed they each have one person who returned a positive test.
It comes after 10 positive tests in England’s second tier and seven in League Two on Saturday.
In the Championship, 1,094 people were tested over the past four days and those who are positive will self-isolate in line with EFL guidelines.
In League Two, a total of 126 players and staff were tested but all came back negative.
More than 4,000 tests on players and staff have been carried out in the Championship since 21 May, with 24 individuals testing positive.
The Championship has set a provisional restart date of 20 June and players have been back in training for more than a week. Only those who have returned negative tests are allowed to enter training grounds.
So far, Preston, Sheffield Wednesday, Cardiff, Middlesbrough, Blackburn, Fulham and Hull City are the only clubs to have confirmed their players or staff have tested positive for coronavirus.
Preston, whose striker Jayden Stockley is self-isolating after testing positive at the weekend, said they had now carried out 186 tests.
“The person had received negative results in all his previous tests, but undertook his latest swab on Monday of this week, which has now provided a positive result,” a club statement added.
Sheffield Wednesday, whose manager Garry Monk had earlier said he believed the Championship should restart a week after the Premier League, said the staff member who tested positive had no symptoms but was self-isolating.