A number of NBA players recently tested positive for COVID-19 for a second time as the league grapples with a rise in cases, sources told ESPN's Brian Windhorst and Zach Lowe.
According to the CDC, reinfection occurs when a previously infected person fully recovers before becoming infected again. The CDC confirms more investigation into immunity from COVID-19 is required, though reinfection is expected - albeit in rare circumstances - based on the habits of similar viruses.
The league confirmed more than 100 cases of COVID-19 since last summer, though the number is expected to be much higher when tracking back to March 2020 when testing was less readily available, Windhorst and Lowe add.
It's also uncertain how many players became infected during the league's shutdown or how many positive results for asymptomatic individuals were unknowingly false positives.
Brooklyn Nets star Kevin Durant and Miami Heat big man Bam Adebayo - both of whom previously tested positive - were recently placed into week-long quarantines for potential exposure to an infected person, highlighting the risks of reinfection.
Many players have reportedly been tested for the antibodies that enable immunity, though no league-wide testing procedure currently exists.
A recent spike in cases among players and staff, and game cancellations stemming from players being placed into the league's health and safety protocols have cast doubt on the 2020-21 season. On Tuesday, the NBA postponed two more games, raising the total to six on the season.
The league, its board of governors, and general managers have reportedly held discussions in the last few days to consider protocol changes that would help restrict the spread of COVID-19. The lengths of practices and shootarounds and limits on pregame and postgame socialization between players were reportedly among the topics discussed.
Stricter rules governing mask-wearing have also been proposed, according to ESPN's Adrian Wojnarowski.