robert sigel. sig. regeneron made headlines when we learned president trump was using it when he had covid-19. now texas governor greg abbott is using it. he has breakthrough covid, apparently not very sick. we first heard about regeneron used for covid at the same time we heard about hydroxychloroquine so i think people are skeptical and wonder if it's legitimate. tell us what we know. >> yes, this is legit. and you have to remember that at first it was being used when there was no vaccine available so it's not really a substitute for vaccination. just to be perfectly clear about that. to back up a little bit. when you get infected or if you get a vaccine, your body produces a strong immune response that will basically try to protect you if you ever get infected again and one of the parts of that immune response is to make antibodies. what regeneron is antibodies to the virus but instead of getting them from your immune system or someone else's, these are made using a powerful technique called monoclon