transmissibility. and whether or not the sharp rise in south africa is truly due to this variant, we don't know, so i think, you know, a way of saying that there is a lot more we don't know than do know. the delta variant is by far the most transmissible we've seen and it tack -- it takes a lot to out-compete delta and i'm not panicking by any means but we have to be thoughtful and how rapidly it is transmitted and whether it is indeed more transmissible to delta, i'm not confident of that yet and then if it does have some immuno-escape property, would it be partial in immuno-escape. so all of this is a consequence of not vaccinating the world and that's number one what we have to do on a global scale, here in the u.s., you have to make sure you're up to date on the your covid vaccines and if you've not gotten that third immunization get it, and if you're infect and