evidence: The parallel execution of several stages of development that would usually be conducted in sequence, such as combining phase I and phase II clinical trials or building manufacturing capacity while the trials are still under way, has allowed pharmaceutical manufacturers to advance much more quickly through the development process than is typical for vaccines.2 One year after the first case of COVID-19 was diagnosed in the United States, three of the vaccines supported by BARDA funding had received emergency use authorizations from the FDA, and two other vaccines were in phase III clinical trials. (It ordinarily takes several years of research and testing before a candidate vaccine enters phase III clinical trials.3 Seasonal influenza vaccines take much less time to develop and approve because their technologies, and the regulatory and licensing procedures for those vaccines, have been used before.) According to the World Health Organization, more than 200 candidate COVID-19 vaccines were in development in February 2021.4 1. Most of the manufacturers have also received research support from or signed advance-purchase agreements with the European Union, several national governments, and two global partnerships supported by foundations and other donors (Coalition for Epidemic Preparedness Innovations and Gavi, the Vaccine Alliance).