Nosek did not return to play in the third period of the Knights' 5-4 win at home over the Anaheim Ducks on Tuesday night.
According to the NHL, Nosek was pulled "upon notification" that he had "returned a positive test," which was "in precise accordance with the terms of the league's COVID Protocol." Nosek was immediately isolated from his teammates and close contact tracing started.
All media availability with both teams was canceled after the game. Nosek was placed on the NHL's COVID protocol-related absences list on Wednesday.
Anaheim coach Dallas Eakins said his team didn't find out about Nosek until after the game but that the NHL put "everybody on red alert" in canceling media availability.
"It's a good call by the league to shut it down and get everyone away from each other," he said.
The NHL said that the Golden Knights' game against the Anaheim Ducks on Thursday night is still scheduled. Rapid PCR point-of-care tests will be administered to all players and staff on both teams in advance of that game, in addition to the daily lab-based PCR testing.
While Nosek was the first player to be pulled from a game for a positive test, he isn't the first to be pulled because of the NHL's COVID-19 protocols. Montreal Canadiens forward Josh Anderson was removed from a game in January after experiencing flu-like symptoms. He went on to test negative for COVID-19. In both cases, the teams completed their games.
Eakins said he wasn't surprised that the Ducks' game against Vegas was allowed to finish after Nosek was pulled.
"I have an inside track on what's going on with our leadership at the very top of the NHL spectrum," he said. "I know what they've gone through. I know how they're employing experts and looking at studies on how many cases are actually confirmed [transmissions] from one team to another team. I had no problem with it last night at all."
The NHL has postponed 34 games this season because of COVID-19 protocols. Of those games, 16 have yet to be rescheduled.
"We're staying diligent within our group. All we can do is hope that the teams we're playing against are doing their best too," Eakins said.