Abstract Background: The coronavirus pandemic9s public health and economic impacts have led to much hope in the US regarding the prospect of a safe, effective vaccine to either prevent infection or minimize symptoms and reduce mortality risk. However, recent US polls indicate a concerning level of hesitancy that will likely lead to suboptimal uptake if such a vaccine becomes available. This study investigated demographic differences regarding US adults9 intent, uncertainty, and refusal to receive a potential coronavirus vaccine and specific reasons for intention to receive it. Methods and findings: Multivariable analysis of Associated Press (AP)-NORC Center for Public Affairs Research cross-sectional survey data collected in May 2020 from a US nationally representative panel of adults (n=1000). Respondents were asked if they would receive a coronavirus vaccine (yes, unsure, no). Among those answering yes, the specific reasons were: to protect self, family, and community; chronic health condition; and having a doctor who recommends vaccines. Multinomial logistic regression models indicated numerous subgroup differences between participants who indicating (1) uncertainty versus refusal, (2) intent versus refusal, and (3) intent versus uncertainty, with the highest number of significant differences observed in the third comparison. Overall, higher likelihood of intention to receive the vaccine versus uncertainty and refusal were mostly observed among respondents with a college education or greater, White, non-Hispanic racial-ethnic identity, ages 60 or older, and more liberal (versus conservative) ideology. Despite variation in endorsement across the five reasons for wanting to receive the vaccine, subgroup differences were fairly consistent across these specific reasons when comparing respondents endorsing such intentions versus, respectively, refusal and uncertainty in separate analyses. Conclusions: These findings suggest that the approval of a vaccine will potentially face problems with overall uptake due to uncertainty or refusal and contribute to creating significant demographic disparities in COVID-19 morbidity and mortality risk. Ongoing assessment of such attitudes are needed as Phase III trials proceed, but the findings highlight need for measuring uncertainty and its underlying reasons, as well as multiple types of education and outreach efforts for those who are uncertain as well as avoidant.