The 49ers on Wednesday placed wide receiver Trent Taylor on the NFL's reserve/COVID-19 list.
Taylor was placed on the list, along with two undrafted rookies on the practice squad: fullback Josh Hokit and tight end Chase Harrell.
The 49ers also announced the signing of quarterback Josh Rosen to the 53-man roster and veteran receiver Jordan Matthews to the practice squad.
Rosen signed with the 49ers off the practice squad of the Tampa Bay Buccaneers to be available as C.J. Beathard's backup in the Week 16 game against the Arizona Cardinals on Saturday.
Nick Mullens is out after experiencing a serious elbow injury that will likely require surgery.
The 49ers on Tuesday opened the practice window for quarterback Jimmy Garoppolo, who has not played since Nov. 1 due to a high ankle sprain. Garoppolo is not expected to play in either of the 49ers' final two games.
Also, practice-squad quarterback Josh Johnson is not available after being placed on the COVID-19 list on Tuesday.
The 49ers already had guard Colton McKivitz, tight end Charlie Woerner and running back Austin Walter on the reserve/COVID-19 list.
Taylor, who was expected to be the 49ers' top slot receiver, has experienced a difficult season in his return after missing all of last season after complications from foot surgery. Taylor has just 10 receptions for 86 yards while appearing in 12 games.