The National Hockey League implemented updated COVID policies on December 29, 2021, for its 25 U.S.-based teams, shortening isolation times after a positive test to five days, following the lead of other professional sports leagues and the Centers for Disease Control and Prevention.

The CDC announced the shortening of the isolation recommendations Monday because of research into when people are most contagious after contracting the virus and recommended five days of strict mask-wearing around others after someone who tests positive returns from isolation.

NHL players, coaches and team staff who test positive can return to their teams after five days if they are asymptomatic or return a negative PCR test, or two negative rapid tests taken over two hours apart.

The changes in the NHL apply to the 25 teams in the U.S., but not the seven Canadian teams because Canada's health department still recommends 10 days.

Tuesday, nine NHL games were postponed in Canada because of COVID issues and attendance limits from local governments.

The new protocols will remain in effect for 14 days, after which the league and NHL Players Association will review how the protocols have worked so far and discuss future adjustments.

Earlier this week, the National Basketball Association and National Football League also followed the CDC advice and shortened isolation times to six and five days, respectively, as both leagues have been wracked by positive COVID tests among their player bases that have caused dozens of key players to miss games.

National Hockey League, COVID Isolation, Sports
The NHL announced December 29, 2021, updated COVID policies shortening isolation requirements after a positive test. Above, San Jose Sharks center Tomas Hertl celebrates with Jayden Halbgewachs (89), Mario Ferraro (38), Noah Gregor (73) and Brent Burns (88) after scoring a goal against the Arizona Coyotes during the third period of an NHL hockey game December 28, 2021. Tony Avelar/Associated Press

Deputy Commissioner Bill Daly confirmed the new protocols, which were first reported by Daily Faceoff.

"I think that's a good step," Nashville Predators forward Filip Forsberg said on a video call. "Obviously testing will still be a regular thing, I'm sure, and that's something that we dealt with all last year, so we're used to that. But I think that's the way to do it as long as we can keep everything in the way it's been, which has been pretty safe to me."

The 10-day isolation requirement remains in Canada.

Hockey players this week had expressed a desire for shorter isolation times. Daily testing and enhanced protocols, including mask-wearing at team facilities unless on the ice for games or practices, are in effect through at least January 7.

The league has postponed 80 games so far this season, counting the nine in Canada because of crowd restrictions in the provinces of Quebec, Ontario and Manitoba. Another game, scheduled for January 12 between the Canadiens and Bruins, was moved from Montreal to Boston, where fans are permitted.

The Associated Press contributed to this report.

National Hockey League, COVID Isolation, Sports
The NHL announced updated COVID policies December 29, 2021, shortening required isolation times following a positive test. Above, a view of the NHL crest on a net prior to the start of the first period between the Montreal Canadiens and the Los Angeles Kings at Centre Bell on November 9, 2021, in Montreal, Canada. Minas Panagiotakis/Getty Images