KFF COVID-19 Vaccine Monitor: The Increasing Importance of Partisanship in Predicting COVID-19 Vaccination Status

The KFF COVID-19 Vaccine Monitor is an ongoing research project tracking the public’s attitudes and experiences with COVID-19 vaccinations. Using a combination of surveys and qualitative research, this project tracks the dynamic nature of public opinion as vaccine development and distribution unfold, including vaccine confidence and acceptance, information needs, trusted messengers and messages, as well as the public’s experiences with vaccination.

The data for this analysis comes from the October 2021 KFF COVID-19 Vaccine Monitor. See the initial report for the survey’s full methodological details.

The KFF COVID-19 Vaccine Monitor and other surveys have consistently shown a strong relationship between partisan identification and how individuals view and experience the COVID-19 pandemic, on questions ranging from worries about getting infected, to self-reported behaviors like mask-wearing and social distancing, to views on vaccinations. This new analysis shows that although COVID-19 vaccination rates have increased over time with majorities across partisan groups reporting being vaccinated, Republicans make up an increasingly disproportionate share of those who remain unvaccinated and political partisanship is a stronger predictor of whether someone is vaccinated than demographic factors such as age, race, level of education, or insurance status. These results suggest substantial challenges for any efforts to further increase vaccine uptake among U.S. adults, which may also affect acceptance of booster shots and COVID-19 vaccines for children as eligibility expands.

A Large And Growing Share Of Unvaccinated Adults Identify As Republicans Or Lean That Way

Partisanship has been a strong predictor of views on coronavirus from the early days of the pandemic. For example, KFF polling in May 2020 found that Republicans were less likely than Democrats to report wearing masks and practicing social distancing. Early views of the COVID-19 vaccine were similarly divided along party lines with a majority of Republicans saying they would not get vaccinated in September 2020 (compared to Democrats who were more equally divided in whether they would or would not get a COVID-19 vaccine once it became available).

By April 2021, a majority of U.S. adults (56%) self-reported they had already received at least one dose of a COVID-19 vaccine. Among the 43% of adults who said at that time that they had not yet been vaccinated, about four in ten (42%) identified as Republicans or Republican-leaning independents and about one-third (36%) identified as Democrats or leaned that way, while 16% identified as independents who didn’t lean toward either party. The partisan divide between vaccinated and unvaccinated adults became even more evident as larger shares of the population received COVID-19 vaccines. Now, six months later, in October 2021, one-quarter (27%) of U.S. adults say they have not gotten a COVID-19 vaccine, but the unvaccinated population is now disproportionately made up of those who identify as Republican or Republican-leaning, with six in ten (60%) identifying as Republican or Republican-leaning (compared to about four in ten of the U.S. total adult population1) and just one in six (17%) calling themselves Democrats or Democratic-leaning. See Appendix figure 1 for a full demographic profile of unvaccinated adults from April to October 2021.

At the same time that the role of partisanship in predicting vaccination status has increased, our surveys and other KFF research have shown that racial and ethnic gaps in vaccine uptake have narrowed over time. And while other groups such as the uninsured, younger adults, rural residents, and those with lower levels of education continue to be vaccinated at lower rates than their counterparts, multivariate analysis – a statistical model that separates out the influence of these different factors – indicates partisanship stands out as the strongest single identifying predictor of vaccine uptake.2 See Appendix figure 2 for regression analysis results displaying the relative size of the effects of education, race and ethnicity, and partisanship, while holding other variables (such as age, rurality, income, ideology) constant based on average population.

Demographic And Attitudinal Differences Between Vaccinated And Unvaccinated Republicans

While self-identifying as a Republican or leaning Republican is one of the strongest identification predictors of remaining unvaccinated, it is important to note that a majority (59%) of this group (Republican and Republican-leaners) does report receiving at least one dose of a COVID-19 vaccine.

Similar to the overall differences between unvaccinated and vaccinated adults, unvaccinated Republicans are younger and report lower levels of educational attainment than their vaccinated counterparts. Larger shares of unvaccinated Republicans identify as conservative (68% v. 58%) and live in counties where former President Trump received more votes during the 2020 election (65% v. 52%), although this difference is not dramatic.3 Another geographic characteristic – urbanicity –  distinguishes the two groups, with 27% of unvaccinated Republicans living in rural areas compared to 16% of vaccinated Republicans (similar to the urban-rural divide found in the overall vaccination rates).

Exploring attitudinal differences by both partisanship and vaccination status reveals that there are some minor differences between vaccinated and unvaccinated Republicans in how they think about the seriousness of the pandemic, their own personal risk, and how personal choice vs. collective responsibility factors into vaccination decisions. However, vaccinated Republicans’ attitudes look much closer to those of unvaccinated Republicans than they do to vaccinated Democrats, highlighting the strong correlation between these attitudes and partisanship, regardless of vaccination status.4

For example, vaccinated Republicans are somewhat less likely than unvaccinated Republicans to say the seriousness of the pandemic has been exaggerated in the news (88% vs. 54%), but both groups contrast with vaccinated Democrats, most of whom say the news is generally correct (56%) or underestimates the seriousness of the pandemic (31%). An overwhelming majority of unvaccinated Republicans (96%) and a somewhat smaller but still substantial majority of vaccinated Republicans (73%) say getting vaccinated against COVID-19 is a personal choice, while a large majority of vaccinated Democrats (81%) see it as everyone’s responsibility to protect the health of others. And while vaccinated Republicans are about twice as likely as unvaccinated Republicans to worry that they will personally get sick from COVID-19 (25% vs. 11%), the share that is worried is still substantially less than it is among vaccinated Democrats (46%).


The increasing role of partisanship in determining individuals’ COVID-19 vaccination status presents a challenge for public health officials and messaging related to any efforts to further increase vaccine uptake among adults. The group that remains to be convinced of the importance of receiving a COVID-19 vaccine is disproportionately represented by those who identify as or lean Republican. Compared to their vaccinated counterparts, these unvaccinated Republicans are distinguished by the voting behavior of their neighbors, their sense that the pandemic is being over-stated, and their lack of a sense of personal risk: factors that may be extremely difficult to overcome in gaining acceptance of COVID-19 vaccines. These findings may also have implications as the vaccine rollout expands to younger children and the CDC recommends booster shots for some adult populations. With most vaccinated Republicans saying they’re not worried about getting sick and 38% of fully vaccinated Republicans saying they do not plan to get a booster shot when eligible, it seems likely that partisanship will continue to play a role in the vaccine rollout beyond the initial effort to vaccinate the adult population.


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