The NBA has not, and is not, mandating that all players be vaccinated against the COVID-19 virus. That said, unvaccinated players -- assuming they are not already being barred from facilities because of state mandates enforcing their own vaccine requirements (New York and California) -- have been subject to stricter protocols.
One of those protocols has been game-day testing, which, as of Dec. 17, will expand to even vaccinated players who haven't received a booster dose, per Shams Charania of The Athletic.
Sources: Beginning Dec. 17, NBA players who have not received booster COVID-19 dose will be subject to game day testing. Also on Dec. 17, team personnel who have yet to receive booster are no longer permitted to interact with players, travel with team or continue as Tier 1.
— Shams Charania (@ShamsCharania) December 4, 2021
If you're wondering what Tier 1 means with regard to the team personnel, it's anyone working regularly within 15 feet of players and referees. Those people, as stated above, will have to get a booster dose as well to continue operating with full clearance.
Hopefully this won't be a problem. It was reported just prior to the season that 95 percent of NBA players had been vaccinated, so it would stand to reason those same players would be OK with getting a booster shot. But you never know how an individual is going to feel about extra doses, particularly those who were hesitant to get the vaccine in the first place but ultimately complied.