Adding to anxiety currently affecting the NBA amid a spike in COVID-19 cases, multiple players who previously tested positive for the coronavirus have recently tested positive a second time, sources told ESPN.

The CDC defines "reinfection" as a person getting infection, recovering and then later becoming infected again. There are ongoing studies about how long immunity might last, but the CDC says it expects some coronavirus reinfections.

The NBA has announced more than 100 positive tests since last summer, but the actual number since March is believed to be significantly higher. Several teams have more than 10 players who have tested positive at some point over the past nine months, sources told ESPN.