That means Dallas could be without Parsons on Saturday night when it takes on the Eagles in the teams' regular-season finale in Philadelphia.
Under a new agreement between the NFL and NFL Players Association released last month, isolation time for players with the virus, regardless of vaccination status, is now five days. But that's contingent on the player being asymptomatic, or at least demonstrating that his symptoms are resolving, after that shortened period.
"I saddened by the news I feel like I let my team down and Dallas cowboys nation!," Parsons wrote on Twitter. "I'll be back better than ever!! I'm only going to be more hungry! See you soon."
Parsons has starred for the Dallas defense since being taken 12th overall out of Penn State in last year's draft. His 13 sacks rank sixth in the league, and he is vying for the NFL's rookie sack record of 14.5, set by Jevon Kearse in 1999. He also was named a Pro Bowler last month, and he's the front-runner for NFL Defensive Rookie of the Year.
Dallas already has clinched the NFC East title and currently would be the No. 4 seed in the NFC playoffs.
Also Wednesday, the Cowboys activated linebacker Keanu Neal from the reserve/COVID-19 list.