is hospitalized in serious condition after telling his followers they did not need to get vaccinated. in friday he regrets not being more vehemently pro vaccine. he wants to more vigorously advocate that as soon as he's on the air. the city of st. louis will be requiring masks again in public spaces and on public transportation on monday. it's reverting back to safety measures. health experts warning that breakthrough infections among people fully vaccinated can and do happen especially with the delta variant spreading. >> what the cdc needs to do is start getting us the answers to what is the rate of breakthrough infections? is it one in 1,000, one in 10 or we really don't know. >> reporter: despite those