Steelers quarterback Ben Roethlisberger, offensive lineman Jerald Hawkins, running back Jaylen Samuels and linebacker Vince Williams were placed on the reserve/COVID-19 list on Tuesday morning, the team said.
All four players will be isolated for five days and are not permitted in the UPMC Rooney Sports Complex but may take part in virtual meetings, the Steelers said.
The team said that the players must pass COVID-19 tests throughout the week before being "potentially eligible to play" against the Cincinnati Bengals on Sunday.
A fifth player, tight end Vance McDonald, was placed on the reserve/COVID-19 list on Monday evening.
On Saturday, the Steelers confirmed that a staff member had tested positive for the virus.
Also last week, the Steelers organization and head coach Mike Tomlin were fined by the NFL for mask violations. The Associated Press reported that Tomlin was among the coaches cited for "not wearing face coverings at all times on the sidelines" during Pittsburgh's game against the Baltimore Ravens on Nov. 1.