FOX Sports' Jay Glazer first reported the development. Rams coach Sean McVay said Allen is recovering well during a segment on FOX Football Now.
"I talked to him yesterday. I'm really glad to hear he's feeling good, he's healthy and he's on the road to recovery," McVay said. "I think we all understand that the severity of what this has meant for some people, fortunately for Brian, he's on the road to recovery. I think he did a great job of letting us know right away so we could be timely in our response and making sure that we didn't expose anybody else to that."
The 24-year-old Allen started nine games for the Rams last year before being placed on injured reserve. McVay said the team completely shut down its facilities "for the last couple weeks" following Allen's test. NFL Network's Omar Ruiz reported Allen had been at the complex to rehab, which the NFL permitted for injured players amid leaguewide shutdowns beginning March 25.
McVay noted the Rams' facilities are scheduled to reopen next week exclusively for players on rehab programs.
"We're going to be real specific in segmenting it so that there's still the social distancing where guys are far apart and really breaking it up throughout the day," he said. "It's a really small group of guys, so we're being as smart and as sound with our decision-making while being able to carry on as close as you can with some of those rehab players."