A day after the N.H.L. announced it would start its winter break early because of a surge in coronavirus cases, the N.B.A. on Tuesday said that it had no plans to shut down for Christmas. In fact, Commissioner Adam Silver said the league had a responsibility to keep playing.

“Frankly, we’re having trouble coming up with what the logic would be behind pausing right now,” Silver said in an interview with ESPN, adding, “It seems for us that the right and responsible thing to do, taking all the factors into consideration, is to continue to play.”

The N.B.A.’s approach is much like that of most other North American team sports leagues, which appear determined to keep playing games and welcoming fans even as they scramble to fill rosters with athletes who are able to play.

Although the N.B.A. does not plan to postpone any of its five nationally broadcast games on Christmas Day, which has become its annual showcase, it is busy devising contingency plans in case a team scheduled to play on Saturday has an outbreak of the virus.

The league sent a memo to teams on Tuesday, warning of potential changes to start times on Saturday. The memo, obtained by The New York Times, said changes could be made until Friday, Christmas Eve.

The N.H.L. announced on Monday that it would pause games and practices for five days, with practices resuming Sunday and games resuming Monday. So far, it has been alone among sports leagues in pausing a season amid the spread of the highly transmissible Omicron variant. While the N.H.L. had planned to go ahead with the two games scheduled for Tuesday, one of those games was postponed because of coronavirus protocols, anyway.

The N.F.L., marching toward the playoffs and the Super Bowl, had no plans to pause its season, even as its list of players sidelined because of Covid protocols had swelled. On Friday, the league moved three weekend games to Monday and Tuesday.

The N.B.A. has used Christmas to showcase its best teams and story lines. This year, though, the games may not resemble the marquee matchups that were expected when the season started.

More than 100 players and coaches have entered the N.B.A.’s coronavirus protocols in December alone, according to team injury reports and news conferences. Seven games have been postponed, including five announced on Monday. Teams are flying in players from their developmental league, or those who have been out of the N.B.A., to fill holes in their rosters.

The only N.B.A. team that has reduced crowd sizes is the Toronto Raptors, who, because of restrictions in Ontario, have limited capacity to 50 percent.

European sports were facing similar disruptions. In England, where six of last weekend’s 10 Premier League games were postponed after virus outbreaks left teams short of players, league officials continued to reject calls from some clubs to cancel more matches, and a busy holiday season of matches remained in doubt.

In Scotland and Wales, government leaders announced that they would impose significant restrictions on fans in stadiums starting Sunday. Scottish sporting events will be “effectively spectator-free,” the country’s leader, Nicola Sturgeon, said, with crowds at outdoor events capped at 500 for as long as three weeks. In Wales, all sporting events will now be held behind closed doors for the same period.

Those kinds of crowd restrictions had been in place in parts of Germany for weeks. On Tuesday, though, Chancellor Olaf Scholz said Germany’s regional bans on spectators and crowds would go national starting next Tuesday as part of a set of strict new rules that will limit the size of New Year’s parties to 10 people, close bars and nightclubs, and empty the country’s soccer stadiums.

“This is not the time for parties and cozy evenings with lots of people,” Scholz said.

Britain’s conservative government, under fire from critics over its handling of the pandemic and from allies who reject the idea of new lockdowns, has shown little interest in closing stadium doors again ahead of a crowded holiday soccer schedule. And the Premier League appears to be following that lead.

“While recognizing a number of clubs are experiencing Covid-19 outbreaks and challenges,” the Premier League said after a meeting of its clubs on Monday, “it is the league’s collective intention to continue the current fixture schedule where safely possible.”

Coronavirus cases in the Premier League more than doubled last week, to 90 from 42, and officials revealed that only three-quarters of the league’s players had received two vaccine doses and that 16 percent were unvaccinated — a stark contrast from soccer leagues in Spain and Italy but also American leagues like the N.F.L., the N.B.A. and the N.H.L., which have generally reported vaccinated rates of 95 percent or higher.

The N.B.A. is a highly vaccinated league. Silver said 97 percent of the league’s players had been vaccinated. According to a person familiar with the league’s numbers, 63 percent of the players eligible for a booster shot — those who are six months removed from completing their initial vaccine sequence — have been boosted. All players who are eligible but have not received booster shots are subjected to game-day testing.

Silver said 90 percent of the league’s positive cases were from the Omicron variant. He also said only a small number of players and coaches who have received three doses of a coronavirus vaccine have experienced breakthrough cases.

“We’re finding ourselves where we sort of knew we were going to get to for the past several months, and that is that this virus will not be eradicated and we’re going to have to learn to live with it,” Silver said in the ESPN interview. “That’s what we’re experiencing in the league right now.”

In March 2020, the N.B.A. was the first sports league to shut down operation because of the coronavirus when Rudy Gobert of the Utah Jazz tested positive for the virus. League officials are hoping they can provide a different kind of example this time.

“Our ability to find a way to keep operating is also significant for society,” Silver said in the interview, “to show that there are ways, despite living in this Covid era, that we can find a safe and responsible way to keep going.”

Andrew Das contributed reporting.