However, where there are unvaccinated people, either because they haven't accepted the vaccination or they don't have access to it, delta is going to continue to drive large waves that are deadly. that's why, fareed, it's so important that the world come together and further scale up the mrna technologies. this is our best insurance policy against both more dangerous varniants which could evade vaccines and against problems with production with many of the other vaccine types. d >> devi, what does this mean, though, for the -- you know, the mythical herd immunity? because it seems like even in...