This paper was written for the NBER Entrepreneurship and Innovation Policy and the Economy (EIPE) meeting held April 27, 2021. The authors wish to thank the organizers, Josh Lerner and Scott Stern, for thoughtful comments on an earlier version. Comments from participants at the meeting are also highly appreciated. The authors also thank Katalin Karikó for helpful responses to our emails and her willingness to review our discussion of mRNA research. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. NBER working papers are circulated for discussion and comment purposes. They have not been peer-reviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.