teens have yet to get the shot. >> what you have now is you have an undervaccinated or relatively unvaccinated population of children with a highly contagious virus, and this virus is seeking out the susceptible. and that is children. >> reporter: massachusetts 12-year-old mikayla decelle has asthma. she was infected alongside her father mike. both of them are unvaccinated, and both were taken to intensive care. >> you got to really protect yourself, you know what i mean? even if you don't have any underlying health problems, you gotta protect yourself. get vaccinated. i should have did it. >> reporter: today in yonkers, new york, parents lining up with their kids, waiting for covid tests to return to school monday. but 1 in 4 of the district's tests are coming back positive. >> we want our kids in a classroom setting. we want them learning. but at the same time, we have to do so in a safe manner. >> reporter: today, the national case average climbing past its already record-breaking heights to a staggering 316,000 a day.