What prevented the Chicago Cubs’ recent COVID-19 situation from spiraling? A cautious approach and getting a number of Tier 1 personnel vaccinated, experts say.

Zachary Binney, a sports epidemiologist and assistant professor at Oxford College of Emory University, and Dr. Carlos del Rio, the executive associate dean at Emory’s medical school, aren’t surprised Young and Driver tested positive even with some level of vaccination protection against the virus. (Young was two weeks post-second shot on Sunday when he tested positive while Driver was between his two shots.) The vaccine doesn’t prevent 100% of people from becoming infected, rather it lessens the severity of the virus for those who get it.