The decision follows the review of the incident on Sept. 25 in which Miami Dolphins quarterback Tua Tagovailoa suffered an apparent head injury and was later allowed to re-enter the game. The league and union jointly announced the findings of the review on Saturday.
Under the new protocols, players will be unable to compete if they are experiencing ataxia.
The joint announcement described the conclusion and findings of their review of Tagovailoa's injury as follows:
"While the investigation determined that the team medical staff and unaffiliated medical professionals followed the steps of the Protocol as written, the NFL and NFLPA agree that the outcome in this case is not what was intended when the Protocols were drafted.