need to get pfizer as a booster, can i get something else and what if i got moderna first? this study, not huge, just over 450 people. it found that mixing and matching worked just fine and was safe and folks who got johnson & johnson first, they were actually better off if they got a booster from pfizer or moderna. they were actually better off if their booster was not johnson & johnson this. group today, the fda advisers will be talking about this study today but they won't be doing anything about it. we won't see mixing and matching come out of this meeting, but it's more of a start of a conversation, and in the future maybe there will be some provisions for mixing and matching. john? >> elizabeth cohen, thanks for kicking us off and especially great for the important context. let's continue the conversation with dr. carlos del rio of emery school of medicine. doctor, grateful for your help. the big booster question today is do you authorize the booster for johnson & johnson, but as you just heard elizabeth cohen say, and you're familiar with