Mayer (concussion) is not participating in Wednesday's practice, Ryan McFadden of ESPN.com reports.
Mayer is in the concussion protocol after having been forced out of Las Vegas' loss to the Commanders in Week 3 early, and he hasn't yet progressed to the stage that would allow him limited on-field work at practice. If he's unable to gain full clearance ahead of Sunday's game against the Bears, Ian Thomas will get a chance to work as the No. 2 tight end behind Brock Bowers.