Yesterday afternoon, San Francisco 49ers cornerback Jimmie Ward tweeted out that he did not have a concussion. That tweet was subsequently deleted, but Matt Barrows has confirmed with Ward's agent that the rookie was not diagnosed with a concussion. This means he will not go through the concussion protocol, and should be cleared for Sunday's game against the Chicago Bears.
49ers defensive coordinator Vic Fangio discussed the secondary on Tuesday during a radio interview. Fangio said Tramaine Brock (toe) and Chris Culliver (concussion) were making progress, and the team was hopeful to have them. If Brock has turf toe, it is entirely possible he misses a couple games. And Culliver's concussion will take a few days at least to get through the concussion protocol.
If one or both is unable to go, Chris Cook will likely be active, and Perrish Cox is also likely to move into the starting lineup. Cox was the first defensive back off the bench when Brock got hurt on Sunday, and that followed a full preseason of work for Cox. Vic Fangio had an interesting description of Cox during his radio interview, referring to him as the utility club in the defense's golf bag. Cox can play nickel and outside, but Fangio also said he has the ability to potentially move out to safety if need be, and would be able to pick it up pretty quickly.
Dontae Johnson had a very solid game, but Cox was solid enough last Sunday that he likely bought himself another start if need be. If both Brock and Culliver can't play, Johnson would likely be the next cornerback into the lineup, with Chris Cook then operating as the primary backup on the outside.