With the US supply of COVID-19 vaccines having increased in recent months and demand starting to level off, most states were at or near having more vaccines available than people who want them as of May 2021. Current efforts to expand vaccine access, such as increasing vaccine supply to community health centers and facilitating access through mobile or pop-up vaccination clinics, will be key to ensuring equitable vaccine availability for communities of color and other communities at high risk of exposure to the coronavirus and death from COVID-19 (Artiga, Corallo, and Pham 2020; Corallo, Artiga, and Tolbert 2021; Dubay et al. 2020; Ndugga, Artiga, and Pham 2021). These efforts will also help the US advance toward herd immunity, meaning between 70 and 85 percent of the population is vaccinated against COVID-19. However, doing so requires sustained focus on vaccine confidence, defined as people's trust in recommended vaccines, the providers who administer vaccines, and the vaccine development process. Confidence in the COVID-19 vaccines has improved since they were first rolled out in December 2020, but about 13 percent of adults in the US still said they would definitely not get a COVID-19 vaccine as of May 2021. Another 12 percent were waiting to see how the vaccines affect people before deciding whether to get vaccinated.