The Pittsburgh Steelers’ pursuit of a perfect season has a new opponent in Covid-19. A day after NFL’s last unbeaten team placed tight end Vance McDonald on the Covid-19 list following a positive test, quarterback Ben Roethlisberger and three other teammates – inside linebacker Vince Williams, running back Jaylen Samuels and offensive lineman Jerald Hawkins – joined it, making their availability for Sunday’s game against Cincinnati (2-5-1) uncertain. The reserve/Covid-19 list is either for players who have tested positive or have been in close contact with someone who has. All players who have been in close contact must quarantine for five days and are unable to visit the team’s practice facility, but can participate virtually. They must pass Covid-19 tests throughout the week to have an opportunity to play. Steelers coach Mike Tomlin said Tuesday it’s possible Roethlisberger and Williams could rejoin the team for its walkthrough practice on Saturday. He pointed to Roethlisberger’s experience as a 17-year veteran as one of the reasons he would have no issue playing Roethlisberger if he’s cleared. The players who are able to practice will work within the constraints of the league’s “intensive” protocols. That includes holding all pre and post-practice meetings remotely as well as requiring players to use the weight room and other services in a rotation to limit the number of people in one room at one time. McDonald, however, will not be available. The team was notified of McDonald’s positive test on Monday morning, hours after the Steelers beat the Cowboys to improve to 8-0 for the first time in franchise history. McDonald immediately self-quarantined. McDonald missed Friday’s practice with an “illness” according to the team’s injury report, but traveled to Dallas with the team and played 24 snaps total against the Cowboys, 20 on offense and four on special teams. Tomlin defended the decision to play McDonald, saying he passed a Covid-19 test after missing practice. The test that revealed the eight-year veteran’s diagnosis was administered on Sunday, with the result not available until after the game. McDonald and Roethlisberger have developed a close relationship since McDonald’s arrival via a trade with San Francisco on the eve of the 2017 season. Their lockers are next to each other inside the team’s practice facility and they have spent a considerable amount of time together before Covid-19 hit. While it’s unclear if McDonald and Roethlisberger sat near each other on the team plane to and from Dallas, Tomlin pointed out the players are required to wear masks at all times while on the flight. Backup quarterbacks Mason Rudolph and Josh Dobbs will both get reps during the week with Roethlisberger elsewhere. Tomlin said the team will “play it by ear” when it comes to figuring out who will be the starter if Roethlisberger is unavailable. The team had been Covid-19 free during the first half of the season, but has still been dealing with the virus. Their game at Tennessee originally scheduled for 4 October was pushed to 25 October because of an outbreak among the Titans. Hours after winning in Baltimore on 1 November, Ravens defensive back Marlon Humphrey tested positive, forcing the Steelers to spend last week in the league’s intensive protocol program.