to be clear, doctor, right, it's still protecting people, right? it protects against a severe disease of over 90% but does that drop concern for you? >> i'm not sure what the real number is because we have data, recent data that comes out of the united kingdom showing a sustained efficacy of 88% for the pfizer vaccine. so i'm not sure how to reconcile the differences between the two studies, what is very clear is that this vaccine in particular, the pfizer vaccine and moderna vaccines, very robust protection against serious illness and death. to give you an example, there have been about 3700 hospitalizations in the united states of fully vaccinated people. that sounds like a big number except the denominator is 170 million. so there are 170 million americans who have been vaccinated, 3700 hospitalized.