with gradient controls. i'm strongly supportive of masking and using effective masking. it is that order that schools should concentrate on right now to basically try to contain the delta variant. >> thanks for the clear guidelines. i want to ask you about vaccines for kids under the age of 12. you now have several health care groups pushing the cdc for approvals. it is one thing for parents, but entirely different for health care groups to say that. what is taking so long? >> first of all, let's go back to the issue of kids and vaccines. look how many kids in the country 12 and older who could be vaccinated who are not vaccinated? some areas, fewer than 15% to 20% are vaccinated. we proved it is not just having the vaccine available. it is getting it in kids' arms.