These vaccines were chosen because their trial results have been published in detail and they have been authorized for use in the United States or in other countries.
Sources of general information about the vaccines, such as their technology, storage conditions, and number of administered doses, are the New York Times Vaccine Tracker and the Centers for Disease Control and Prevention (CDC).
Sources of information about the efficacy and safety of the vaccines are the published clinical trials themselves, U.S. Food and Drug Administration (FDA) documents, and a company announcement from AstraZeneca about the results of its latest trial in the United States. Efficacy data based on completion of recommended number of vaccine injections.
This website is updated as new published data become available.