The Vaccine Monitor was launched by KFF in December 2020 as an ongoing research project tracking the public’s attitudes and experiences with COVID-19 vaccinations. The goal was to accurately capture vaccine intentions and behavior as the vaccine rollout began. KFF sought to provide its audience with an understanding of the barriers to vaccine access, the questions and concerns driving vaccine hesitancy, and the trajectory of vaccine uptake. Beyond the public in general, the interest was in observing differences by groups (e.g. racial and ethnic groups, parents, people living in urban or rural areas) as far as vaccine-related attitudes and behaviors. KFF enlisted SSRS to carry out the task of data collection for the vaccine monitor. This resulted in a series of polls, fielded nearly every month from December 2020 to mid-2022, with over 1,500 respondents every month. Each poll included oversamples of Hispanic and African American respondents, as well as large samples of vaccine-hesitant respondents, and one-off oversamples of parents (as vaccines for children were rolled out), and rural Americans. In total over 30,000 Americans shared their thoughts and experience about the COVID-19 vaccine through this unique and challenging project.


The monthly tracker needed to reach underrepresented, lower-incidence populations. Furthermore, as more and more Americans were getting the COVID-19 vaccine, it was likely to hear from a large enough number of unvaccinated Americans, and understand their motivations.


To ensure as representative a sample as possible the majority of data were collected by telephone; pre-dominantly with adults reached by cell phone. This meant that SSRS interviewers spent tens of thousands of hours throughout this time-period calling Americans across the country and asking to hear their viewpoints. This also required an intricate sampling approach to reach enough respondents from the various groups of interest. SSRS methodologists identified areas (and telephone numbers) likelier to belong to Hispanics and African Americans. We oversampled prepaid, or pay-as-you-go, phones, that are likelier to be used by lower-income adults, and Spanish-speakers. To reach the vaccine-hesitant, sampling put an emphasis on counties where relatively smaller shares of people received a vaccine. And then, our statisticians, weighted the sample to ensure that sample design and non-response are not affecting the final outcome.


The KFF Vaccine Monitor was a reliable predictor of public health behavior, regularly reported in the news media. The data offer not only an accurate account of vaccine uptake over time and by group (https://www.kff.org/coronavirus-covid-19/dashboard/kff-covid-19-vaccine-monitor-dashboard/#vaccines), but a wealth of information for the public and stakeholders alike, to understand barriers to vaccination, and possible approaches to persuading more Americans to get the vaccine.