Harris was hurt five minutes into Sunday's 13-12 win. Hoomanawanui went out on the last play of the third quarter.
The Rams have been bothered by injuries all season. Coach Steve Spagnuolo said 15 players will be either out or limited this week. Quarterback Sam Bradford took a helmet to the thigh on Sunday, but will won't be limited according to Spagnuolo.
St. Louis listed seven players as inactive before the game at Cleveland.