Boston Celtics center Al Horford available for Game 2 against Miami Heat - ESPN

For a player to return to game action after testing positive for COVID-19, there had been two paths to a return: either recording two consecutive negative PCR tests at least 24 hours apart, or return two consecutive PCR tests sampled at least 24 hours apart with cycle threshold values greater than 30 beginning no sooner than Day 4 and 5 after initially testing positive.

In that circumstance, a player could return to team activities if he returns two consecutive "not detected" results from PCR tests collected on game day.

The Celtics also announced that Derrick White would miss Game 2 for personal reasons, as he and his wife are expecting a child.