Abstract
In December 2020, the US Food and Drug Administration issued emergency use authorizations for two mRNA vaccines against coronavirus disease 2019. These vaccines represent an incredible scientific achievement and a major step in efforts to bring the global pandemic to a close. However, these vaccines create many logistical challenges that limit just how far-reaching their impact can be. This commentary reviews how these vaccines offer immunity, summarizes the Phase III trial results, and offers a discussion of the challenges that remain after these vaccines are introduced for widespread use.