As of February 8, 2021, 59.3 million doses of vaccines to prevent coronavirus disease 2019 (COVID-19) had been distributed in the United States, and 31.6 million persons had received at least 1 dose of the COVID-19 vaccine (1). However, national polls conducted before vaccine distribution began suggested that many persons were hesitant to receive COVID-19 vaccination (2). To examine perceptions toward COVID-19 vaccine and intentions to be vaccinated, in September and December 2020, CDC conducted household panel surveys among a representative sample of U.S. adults. From September to December, vaccination intent (defined as being absolutely certain or very likely to be vaccinated) increased overall (from 39.4% to 49.1%); the largest increase occurred among adults aged ≥65 years. If defined as being absolutely certain, very likely, or somewhat likely to be vaccinated, vaccination intent increased overall from September (61.9%) to December (68.0%). Vaccination nonintent (defined as not intending to receive a COVID-19 vaccination) decreased among all adults (from 38.1% to 32.1%) and among most sociodemographic groups. Younger adults, women, non-Hispanic Black (Black) persons, adults living in nonmetropolitan areas, and adults with lower educational attainment, with lower income, and without health insurance were most likely to report lack of intent to receive COVID-19 vaccine. Intent to receive COVID-19 vaccine increased among adults aged ≥65 years by 17.1 percentage points (from 49.1% to 66.2%), among essential workers by 8.8 points (from 37.1% to 45.9%), and among adults aged 18-64 years with underlying medical conditions by 5.3 points (from 36.5% to 41.8%). Although confidence in COVID-19 vaccines increased during September-December 2020 in the United States, additional efforts to tailor messages and implement strategies to further increase the public's confidence, overall and within specific subpopulations, are needed. Ensuring high and equitable vaccination coverage across all populations is important to prevent the spread of COVID-19 and mitigate the impact of the pandemic.