It is the third time Welker has gone through the concussion protocol since Nov. 17.
Under the guidelines of the protocol, Welker did not participate in the Broncos' practice Monday. He was cleared on Wednesday to travel with the team to Dallas for Thursday's preseason finale, but he's still under the guidelines of the concussion protocol and not cleared to return to practice or play in a game.
Asked how Welker's spirits were, Fox said after the team's workout: "Very good. Talked to him this morning. He's feeling good. ... He'll be out there when he's healthy."
Also asked about the severity of Welker's concussion this time, Fox said: "I can't give a level. It's just a concussion. I don't think there's part concussion, half concussion. Either you're concussed or you're not, the way I understand it."
Per the protocol, to be eligible to return to full participation in practice in time for the Sept. 7 regular-season opener against the Indianapolis Colts, Welker would have to be symptom-free by Monday.
"Our first priority is his safety and well-being," Fox said. "... I know as an organization his well-being is our first priority. ... We just take it one day at a time. We'll see how he gets through today, and I get updated on every day medically on every player, including Wes in this case. We'll see what tomorrow brings."
With three concussions in such a short span for Welker, there has been some discussion in the public domain and on social media about whether the 33-year-old Welker should consider retirement. Fox said that subject has not been a part of his talks with Welker since Saturday's game.
"That's not been brought up at all," Fox said. "... I didn't sense that."
Fox added that the hit, by Texans safety D.J. Swearinger, is "part of football."
"It was penalized," Fox said. "... Those are things that happen in a game, whether it's our team or the opponent. It's football, and it happens. It's part of the game. Obviously we're disappointed in the results, but it happens during games, it's happened to our players, and I'm sure it will moving forward as well."
In addition to Saturday, Welker left a game Nov. 17 against the Kansas City Chiefs with a concussion and was also reported by the team to have a concussion when he left a Dec. 8 game against the Tennessee Titans. Welker did return last season to play in the Broncos' three postseason games, including Super Bowl XLVIII, wearing a helmet with extra padding.
Welker has continued to wear the helmet this season.
According to the league's concussion protocol, even if a player is symptom-free the day after his concussion, he can return only to light exercise three days after the hit and only in noncontact portions of practice four days after the hit. The quickest a player who is symptom-free the day after suffering the concussion can return to a full-contact practice is five days after the hit, which is Friday in a normal game week.
Also per the policy, once a team doctor has signed off on a player's return to the field, a doctor unaffiliated with the team and approved by both the NFL and NFL Players Association must also clear the player to return. One of the factors considered, in addition to the cognitive tests, is a player's concussion history.