O'Reilly, who tested positive for COVID-19 on Tuesday, will miss at least the next four games after experiencing symptoms. Saad, who tested positive Oct. 21, will miss at least the next two games.
Saad has missed the past two games and will not play against the Colorado Avalanche on Thursday (8 p.m. ET; BSMW, ALT, ESPN+, NHL LIVE) or against the Chicago Blackhawks on Saturday. The forward has scored two points (one goal, one assist) in three games this season,
The earliest O'Reilly can return to the lineup is Nov. 7 at the Anaheim Ducks. The center has scored five points (two goals, three assists) in five games.
"It's obviously not very good news for O'Reilly, his health and the team for sure," Blues coach Craig Berube said. "It's an obstacle that we're going to have to deal with just like we had to with Saad.
"... I found out when I got to the rink. Obviously it's upsetting and surprising at the same time, but it's not something that we want to hear, that's for sure. Again, we'll deal with it. O'Reilly's out at least 10 days, I believe. I'm just not sure on Saad yet when he's back. It's getting close though."