(KRON) — San Francisco 49ers quarterback Brock Purdy is in concussion protocol, head coach Kyle Shanahan told reporters on Wednesday. Purdy started to have concussion symptoms on the plane ride home after the 49ers’ 22-17 loss to the Vikings in Minnesota on Monday night.

If Purdy, 23, is not cleared by the team’s next game this Sunday, backup quarterback Sam Darnold is expected to start at home against the Cincinnati Bengals on Oct. 29.

Against the Vikings, Purdy completed 21-of-30 passes for 272 yards and one touchdown, along with two interceptions.

Other notable 49ers injuries include Deebo Samuel (shoulder) and Trent Williams (ankle). Both will not practice on Wednesday.

The 49ers are 5-2 and are atop the NFC West standings. San Francisco, along with the Lions (5-2), is behind the Eagles (6-1) for the top spot in the NFC standings.

Implemented in 2018, the NFL’s Concussion Protocol is a multi-step process that requires players to go through a checklist before returning to game action.

This story will be updated.