Eight people from six Championship clubs have tested positive for coronavirus in the past week, the English Football League announced on Wednesday.
The results came from 2,213 tests conducted on players and staff from the 24 second-tier clubs, who will resume the 2019/20 season on Saturday.
Four individuals from two of the quartet of League One clubs preparing to compete in the play-offs tested positive, while there were no positive tests among the four League Two clubs.
Individuals who test positive must now self-isolate in line with EFL guidelines, and will not be able to re-enter a club training facility until they have provided a negative test.
The League Two play-offs begin on Thursday, while League One action begins on 3 July.
Championship side Brentford, who restart their season at fellow London club Fulham on Saturday, confirmed on their official Twitter account that one of their staff had returned a positive test.