The finding that the Delta variant resulted in similar viral loads "was a pivotal discovery leading to CDC's updated mask recommendation," Walensky said Friday. Walensky said that ongoing outbreak investigations will help uncover more about what happens when these breakthrough infections do occur. The move has already prompted a number of places, like businesses and school districts, to update their mask policies. It's not just Delta's prevalence and contagiousness that motivated the CDC to update its guidance, but also lower uptake of Covid-19 vaccine than hoped. It also makes sense that, as more and more people get vaccinated, you'll see more breakthrough infections.

Source: CNN July 31, 2021 08:03 UTC