is going to be a three-dose vaccine, just from the way the vaccines were administered, spacing those first two doses together, three to four weeks apart. we would expect to see a decline in immunity, when you give the primary immunization so close together. we knew a third immunization was in the cards, and it's a matter of how quickly we'll see breakthrough infections and breakthrough hospitalizations. i think we're reaching that point. the hope is, and there's data to support that, that by giving the third immunization, those older americans who are getting sick and in the hospital, who are older, who have underlying conditions, we can build up their virus neutralizing antibodies yet again and t chel responses and keep them out of the hospital. >> also, what is happening with covid and kids. one in four new infections are children. 250,000 kids reported infections in the last week.