>> early data and mutation data say this may well be more transmissible than delta. this will take time to sort out. >> let's discuss now with cnn medical analyst dr. jonathan reiner, thanks for joining us. it's not just cases. hospitalizations are also up. the delta variant is dominant now. but more omicron cases are cropping up. the cdc director is sounding the alarm. there is a lot we don't know, but are you worried by what you're seeing at this moment? >> well, i'm worried about delta and i'm worried about the 17% of american adults that have been vaccinated in the united states, the 45 million people that will get infected if they don't get vaccinated. there is a lot we don't know about omicron. it looks like a very