SANTA CLARA (CBS SF) — Just days ahead of their 2020 season opener against the Arizona Cardinals, the San Francisco 49ers announced Wednesday star linebacker Fred Warner was returning to practice after spending time on the NFL’s COVID-19 Injured Reserve list.

Warner was placed on the Reserve/COVID-19 list on Aug. 31st. By league rules, the 49ers were not allowed to say if Warner had tested positive or if he was placed on the list for having come into contact with someone with the illness.

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While not being able to talk about any specific details in relation to Warner’s situation, 49ers head coach Kyle Shanahan said it did serves as a reminder to his teammates of the COVID-19 threat.

“Fred’s back. He’s good to go,” Shanahan said on Wednesday’s Zoom call. “I can’t talk about too much of his week away, but Fred’s been as reliable of a player that we’ve had. It’s great to get him back today. We were obviously pretty nervous about that, but he’s good to go and we’re very grateful he’s going to be here.”

Since the 49ers opened training camp, the team has put into place a number of precautions to limit exposure and spread of the illness.

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During a recent Zoom call, San Francisco star running back Raheem Mostert was asked how seriously he and his teammates were taking the threat of possibly contracting COVID-19.

He reached down and grabbed a small device that was attached to a lanyard draped around his neck.

“This is not a bubble. COVID can come through at any time. We are definitely doing that (taking the threat of COVID-19 seriously),” he said. “That’s why we wear these monitors that blink when we get within six feet of each other.”

This is the NFL in the era of COVID-19. The 49ers have daily testing. Temperatures are taken. Distance monitors worn. Meeting rooms set up for social distancing.

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“If you come into this building and every morning you go through the protocol — waking up at 6:30 a.m.-7 a.m. and meeting start at 9 a.m. and you have to make time to get your COVID testing check in, get your temperature checked — it should be an eye-opener,” he said.