offit, a member of the fda's advisory committee and the author of "you bet your life: from blood transfusions to mass vaccinations, the long and risky history of medical innovation." thanks so much and thanks for writing this book as well, very informative. last month saw the highest number of covid deaths from pregnant women. can you explain why the benefits of this shot outweigh potential risks? >> it's interesting the way this played out. what happened was when pfizer and moderna did their phase 3 trials, they didn't include pregnant women in those trials. typically the cdc will say contraindicated for use in pregnant women because we have no data. but even then the cdc new pregnant women had more risk of severe infection which could cause ventilation and death from covid. so they said pregnant women