historical reasons, white adults are a larger subgroup of the population and, consequently, constituted 59 percent of all vaccine-hesitant nonelderly adults. Figure 2 shows that about 6 in 10 vaccine-hesitant adults were white, roughly the same as their proportion of the full nonelderly adult population. Black adults and Hispanic/Latinx adults each constituted close to 2 in FIGURE 2 Racial and Ethnic Composition of Vaccine-Hesitant Adults Ages 18 to 64 in December 2020 URBAN INSTITUTE Source: Well-Being and Basic Needs Survey, December 2020. Notes: We define vaccine-hesitant adults as those who would definitely not or probably not get a vaccine. “Other” includes non-Hispanic/Latinx adults who are not Black or white or are more than one race. Republicans were nearly twice as likely as Democrats to report they would probably not or definitely not get vaccinated (47 percent versus 25 percent). Differences in hesitancy by political affiliation were largest among white adults, followed by Hispanic/Latinx adults. Willingness to get vaccinated differed significantly by political party affiliation: 24 percent of adults who identify as Republican or lean Republican (Republicans) would definitely not get a vaccine, compared with 10 percent of adults who identify as Democrats or lean Democratic (Democrats). Another 23 percent of Republicans would probably not get a vaccine, compared with 15 percent of Democrats (figure 1). Adults who are independent, affiliated with a third party, or unaffiliated, who constitute 4 percent of the sample, reported hesitance to get vaccinated at a rate similar to Republicans (appendix table 1). Partisan gaps in willingness to get vaccinated were widest among white adults: 48 percent of white Republicans reported they would probably not or definitely not get vaccinated, compared with 18 percent of white Democrats (figure 3). Wide gaps in hesitancy by party affiliation were also found among Hispanic/Latinx adults: 48 percent of Republicans and 24 percent of Democrats reported they would not get vaccinated. Close to half (47 percent) of Black Democrats reported they would probably not (29 percent) or definitely not (18 percent) get vaccinated. We lacked sufficient sample size to examine differences in hesitancy by political affiliation among Black adults. 19 Vaccine Varied by Political Party Affiliation within Racial and Ethnic Groups of Adults Ages 18 to 64 in December 2020 URBAN INSTITUTE Source: Well-Being and Basic Needs Survey, December 2020. Notes: Estimates are not shown for non-Hispanic/Latinx adults who are not Black or white or are more than one race; Black Republicans; and adults who are independent, affiliated with a third party, or unaffiliated. We define vaccine-hesitant adults as those who would definitely not or probably not get a vaccine. Appendix table 1 shows estimates for all response categories: definitely would, probably would, probably would not, and definitely would not. */**/*** Estimate differs significantly from the reference group (^) at the 0.10/0.05/0.01 level, using two-tailed tests. Reasons for Not Getting a COVID-19 Vaccine Most vaccine-hesitant adults were concerned about side effects and vaccine effectiveness. However, more than half (57 percent) thought they did not need the vaccine, and 63 percent of vaccine-hesitant Republicans held this view. Other reasons for being hesitant included worrying the vaccines were not tested enough and lacking trust in the vaccines and their proponents. Table 1 shows 90 percent of vaccine-hesitant adults rated concern about side effects as a very or somewhat important reason they would not get vaccinated, and 84 percent rated wanting to know more about how well the vaccines work as important. These shares varied little by race, ethnicity, or political party affiliation. Just over half (57 percent) reported not needing a vaccine was an important reason for not getting it; Republicans were more likely to say not needing a vaccine was an important reason not to get vaccinated than were Democrats (63 percent versus 51 percent), and adults who would definitely not get vaccinated were more likely than adults who would probably not get vaccinated to rank this as important (64 percent versus 52 percent). 1 Most Vaccine-Hesitant Adults Ages 18 to 64 Reported Concerns about Side Effects and How Well the Vaccines Work as Important Reasons for Not Getting a COVID-19 Vaccine in December 2020 Share Reporting the Following as Very or Somewhat Important (%) Concerned about side effects Want to know more about how well the vaccines work Do not think they need vaccine All vaccine-hesitant adults 90 84 57 Willingness to get vaccinated Definitely would not^ 88 78 64 Probably would not Race and ethnicity Black^ 88 81 54 White 91 86 59 Hispanic/Latinx 90 86 58 Political party affiliation Republican^ 90 84 63 Democrat 90 85 51*** Source: Well-Being and Basic Needs Survey, December 2020. Notes: Estimates are not shown for non-Hispanic/Latinx adults who are not Black or white or are more than one race and for adults who are independent, affiliated with a third party, or unaffiliated. We define vaccine-hesitant adults as those who would definitely not or probably not get a vaccine. Estimate differs significantly from the reference group