The most important bit here is not “double-layered”; it’s “all recruits”. There was no unmasked group for comparison, so this study tells us nothing about mask effectiveness beyond “some people still got infected, so they’re less than 100% effective”.
The most important bit here is not “double-layered”; it’s “all recruits”. There was no unmasked group for comparison, so this study tells us nothing about mask effectiveness beyond “some people still got infected, so they’re less than 100% effective”.