had in may was the alpha variant. and that was a variant that we saw when there was vaccine breakthrough, if there was vaccine breakthrough, that it was not transmissible. remember, the alpha variant was a much less transmissible variant. so fast forward to what we were seeing at the end of june, early july, the beginning of the delta surge. and data were just emerging that demonstrated with delta a much more transmissible variant, that those vaccine breakthroughs were turning out to be able to transmit to other people. it was absolutely new science, and it was important for us, you rely on us to follow that science and change our guidance in response to that science, and that is exactly what we did. >> as you know, the agency which you run has come under criticism for that, people saying, oh, they changed around, they went backwards. to boil down your response, which i understand is nuanced and scientific, are you saying the guidance didn't really change, it was the nature of