Nets’ Kevin Durant and Kyrie Irving Enter Virus Protocols

Irving’s potential return to the Nets is, at least outwardly, an awkward visual for the Nets and the N.B.A. In New York City, the pandemic has continued to rage with the arrival of the Omicron variant, with long lines surrounding testing sites as a result of a surge in cases.

But the virus continues to cause problems across sports. In recent weeks, multiple N.B.A. teams have had to cancel practices, postpone games and place dozens of players in protocols as a result of rising cases. On Friday, the N.F.L. postponed three games as a result of outbreaks, and half of the matches in England’s Premier League this weekend were canceled because of outbreaks on several teams. Medical experts say unvaccinated athletes, like Irving and others, remain the most at risk from the coronavirus.

While 97 percent of N.B.A. players are vaccinated and the league has run advertisements promoting vaccines, Irving remains the most visible vaccine holdout. His stance has made him a particular cause célèbre of conservatives in the United States, such as Senator Ted Cruz, Republican of Texas, who publicly praised Irving for holding out, and those who have spread vaccine misinformation.

Irving has not publicly discussed his unwillingness to receive the vaccine. He has developed a penchant for dipping into controversy throughout his career, however, such as suggesting a serious belief that the Earth is flat.

When Irving was signed by Brooklyn in the summer of 2019, he was made a key face of the franchise along with his close friend Durant. Two years later, the anti-vaccine movement did the same, even protesting on his behalf in front of Barclays before this season’s home opener.

Both Marks and the Nets owner Joe Tsai were publicly steadfast in saying Irving would not be allowed to take the floor part time for the Nets unless he was vaccinated to comply with the city’s mandate. Tsai told ESPN in October that “it is just not tenable for us to have a team with a player that comes in and out, no home games, only away games.”

That same month, Marks told reporters: “Our focus, our coaches’ focus and our organization’s focus needs to be on those players that are going to be involved here and participating fully,” adding, “this is a choice that Kyrie had, and he was aware of that.”