vaccine mandates or mask mandates for that matter. what can parents do to make sure their children are safe if their teachers and peers aren't vaccinated? >> we know how to get kids back into school safely full-time. it includes many of the things you mentioned, vaccinations for everybody. it means good ventilation. it means testing. we have lots of testing capability now. and it does include especially in high-transmission areas mask wearing. and what i would say to parents is first of all if you're in a high transmission area, certainly make sure your kids are masked up. but push for those policies. they're readily available, we have the resources and they can make schools really quite exquisitely safe. >> what is your message to those who have been previously infected and still haven't gotten the vaccine because they feel like they still have protection from their previous covid infection? >> this has come up a lot. it's a really important point. a previous infection does infer some degree of immunity certainly. the big question is is it as good as having been vaccinated