with new concern about that omicron subvariant, there is renewed push under way for another round of booster shots. the fda is expected to authorize this week a second booster for people age 50 and older of both the pfizer and moderna vaccine putting in the former request last week for the second booster but also in doing so, asked to include everyone 18 and older in the authorization. where is this headed? how many shots do you need? joining me is paul burton, the chief medical officer for moderna. thank you for being here. really appreciate it. let's start on this booster news. what do you think of a second booster for people 50 and older really means for wanting further spread? do you think it's necessary? >> kate, i do. look, we've seen all along the natural history of this virus, it's able to make these very large changes that brings with