worried about it, it just seems to have taken on a force of its own? i know two cases in korea, popped up in la and other places, what is it and are you worried about it? >> well, it is a variant that was first seen in colombia and ecuador. in colombia it's like 40% and south america and it does have a whole lot of mutations, ten or so of them that make it different from where we started and some of those are in places that you might worry would interfere with the antibodies or even the vaccine. it's worth tracking, who has called it a variant of interest. cdc hasn't named it that. we have relatively few cases in the u.s. but what i've seen so far and we are tracking this day by day, very carefully suggest that the vaccines still will work quite well against so i'm not quite anxious and look