Daly M, Jones A, Robinson E, et al. - As public trust in the development of vaccines and the government approval process represents a potential crucial reason for the decline in the willingness to vaccinate throughout 2020, researchers sought to determine changes in trust in vaccination and vaccine hesitancy. From 7 waves of the probability-based Understanding America Study (UAS) of US adults, conducted between October 14, 2020, and March 29, 2021, participants were assessed. Questionnaires were administered to the panel members every 14 to 28 days in UAS. The response rate of 75% to 79% was recorded from panel members in this study. Analysis revealed that after an increase in reluctance to vaccinate in 2020, there was a longitudinal decline in reported vaccine hesitancy in late 2020 and early 2021. The regulatory approval of COVID-19 vaccines and rollout of mass vaccination program led to reduction in hesitancy. All demographic groups, especially Black and Hispanic participants, had a significant decline in vaccine hesitancy. This reduction is relevant because these groups particularly showed low COVID-19 vaccine acceptance and have experienced a disproportionate burden of severe illness and death because of COVID-19. Despite these gains, vaccine hesitancy estimates remained high in March 2021, especially among young adults and Black and low socioeconomic status participants.