Cornerback Brandon Harris was not at Texans practice Thursday and is undergoing the same concussion protocol that the NFL institutes during the season.

Harris suffered the injury after a collision with DeAndre Hopkins on Tuesday.

The Texans haven’t had any serious injuries during OTAs, but this week San Francisco receiver Michael Crabtree suffered a torn Achilles, offering a sobering reminder of the possibility.

“You get 10 days, and to be honest with you, you hold your breath every day,” coach Gary Kubiak said. “You want to get better as a team. You catch all the young guys up, but freak accidents happen. We had (Phillip) Supernaw and Sunny (Harris) the first day. (We) weren’t even in a team period — just running an individual drill, and both of them hurt their foot. It’s part of football, but it’s the bad part.

“That’s why you’ll always hear us on their tail to stay off the ground, to protect each other.”