What are emergency use authorization and do they guarantee that a vaccine or drug is safe?

Emergency use authorizations, or EUAs, are used to speed up the process of making a vaccine or medication available to the public sooner than a full FDA-approval. While that does not guarantee that they are completely safe and effective, it does suggest that the risks and benefits are in a reasonable balance. Christopher Robinson and Jeremy Greene share what that means for the new coronavirus vaccines in this Conversation article.