Boston Celtics center Al Horford (42) shoots over Milwaukee Bucks forward Giannis Antetokounmpo, left, during the second half of an NBA basketball game, Monday, Dec. 13, 2021, in Boston. Credit: Charles Krupa / AP

The Celtics are the latest team in the NBA to grapple with health and safety protocols as they listed two more players on the injury report.

Al Horford and Grant Williams are officially out for the 7:30 p.m. Friday game against the Warriors because of the protocols, which the league uses for coronavirus-related issues. Jabari Parker was also deemed out on Thursday’s injury report because of the protocols (Boston coach Ime Udoka said he was feeling ill).

That brings the Celtics up to three players who are in health and safety protocols. It’s unclear how soon or when Horford, Williams and Parker can return. Josh Richardson sat out two games for the same reason but returned to practice this week.

While the Celtics have stayed relatively protocol-free for much of the season — aside from the preseason — the spike in COVID-19 cases are starting to hit them and the league. Multiple teams are seeing disruptions because of the virus, whether through positive test cases or potential close contacts. Boston now joins the list.

The Celtics had two positive COVID-19 cases during the preseason: Horford and Jaylen Brown. While both players came back to miss limited time, it was a reminder the virus was going to have an effect on the season. With Horford back on the list, it’s a concerning look going forward. The league and players’ association agreed to new COVID-19 rules, including increased testing and mask-wearing through the holidays.

Story by Souichi Terada,