nation," he's also a pfizer board member. take a listen. >> given the fact that's changing, that's evolving. new data is accruing, it's hard for fda to give a fixed snapshot of what the efficacy of this clinical data set so if they wait a little longer, if they administer the third dose in that clinical trial, they're not only going to have perhaps a better measure of effectiveness from this trial, but they'll also have a data set, a firm picture of what level of effectiveness the vaccine is delivering. >> and that wait, we might have to wait until april. pfizer said it could have data on its three dose vaccine series in early april. >> just a couple of months away, it's all about the efficacy, and not the safety. jacqueline howard, thank you so much. and still ahead, a former white house adviser who navigated russia's last invasion of ukraine warns that the u.s. cannot underestimate vladimir putin again. we'll speak with her live up next. 'm driving, i see inspiration right through my glass.