Three important members of the 49ers' defensive backfield on Monday were placed on the reserve/COVID-19 list, the team announced.
Nickel back K'Waun Williams, cornerback Dontae Johnson and safety Jimmie Ward went on the COVID list, but they might not be forced to miss a game.
Under the new NFL protocols, Williams, Johnson and Ward are eligible to be activated off the list after five days which would allow them to be available for the 49ers' Week 18 game on Sunday against the Los Angeles Rams.
The team also placed running back Raheem Mostert on the COVID list. Mostert is out for the season after undergoing knee surgery.
Johnson saw action in the fourth quarter of Sunday's game against the Houston Texans when he entered the game in place of Josh Norman, who was called for his sixth defensive pass interference penalty of the season. Johnson could be in line to start against the Rams.
Last Monday, the 49ers placed punter Mitch Wishnowsky on the COVID list. He was cleared on Saturday and played in the 49ers' 23-7 victory over the Houston Texans a day later.
The 49ers signed free-agent punter Colby Wadman last week as an insurance policy in case Wishnowsky was not cleared in time to play. On Monday, the 49ers released Wadman and signed running back Brian Hill to the practice squad.