for the mask wearer against virus that might be floating in their vicinity. so if you're fully vaccinated, you're likelihood of getting the var virus is low and lower if you have the mask on. the main reason is once again we have a lot of community spread. we have people in indoor settings where some are vaccinated and some are not. if we want to try to tamp down this delta variant outbreak, the best thing we can do is get everybody vaccinated and get people to wear masks in those settings. i know people are tired of that. i know they think this seems like a flip-flop but the data has changed. we're not making this recommendation now just for random reasons. we have new evidence that the masks really are going to be important to get us through this if you're indoors. >> the notion of herd immunity which some scientists like you may not have ever fully embraced or liked to begin with. is it now just more or less obsolete, the idea that if we vaccine enough people that covid