combination of vaccinations and masks. we also need to prioritize the kids and the teachers by doing things in the larger community to keep cases down. >> listen, it's all about the risks, right? there's always a risk in sending kids to school. i got my kids an n95 masks. they were wearing cloth before. we're wearing new masks. dr. mina, what role should testing play? in some cities like new york it's not mandatory. in los angeles they are requiring students get tested before they come back to class. what role do you think that should play? >> whether we close down schools is ultimately going to be in some ways -- going to be driven societily, about what risk associatity is willing to take. closing down schools just like the rest of the pandemic is the information problem. the information problem is we don't know who is positive when. so we end up closing things down