Partisan Polarization of Childhood Vaccination Policies, 1995–2020

Kevin Estep, PhD; Annika Muse, BS; Shannon Sweeney, BS; Neal D. Goldstein, PhD, MBI


Am J Public Health. 2022;112(10):1471-1479. 

In This Article

Abstract and Introduction


Objectives: To examine trends in partisan polarization of childhood vaccine bills and the impact of polarization on bill passage in the United States.

Methods: We performed content analysis on 1497 US state bills (1995–2020) and obtained voting returns for 228 legislative votes (2011–2020). We performed descriptive and statistical analyses using 2 measures of polarization.

Results: Vote polarization rose more rapidly for immunization than abortion or veterans' affairs bills. Bills in 2019–2020 were more than 7 times more likely to be polarized than in 1995–1996 (odds ratio [OR] = 7.04; 95% confidence interval [CI] = 3.54, 13.99). Bills related to public health emergencies were more polarized (OR = 1.76; 95% CI = 1.13, 2.75). Sponsor polarization was associated with 34% lower odds of passage (OR = 0.66; 95% CI = 0.42, 1.03).

Conclusions: State lawmakers were more divided on vaccine policy, but partisan bills were less likely to pass. Bill characteristics associated with lower polarization could signal opportunities for future bipartisanship.

Public Health Implications: Increasing partisan polarization could alter state-level vaccine policies in ways that jeopardize childhood immunization rates or weaken responsiveness during public health emergencies. Authorities should look for areas of bipartisan agreement on how to maintain vaccination rates.


Responses to the availability and promotion of COVID-19 vaccines have been influenced by political party. Partisanship is a significant predictor of intent to be vaccinated against COVID-19,[1] actual rates of vaccination,[2] and lawmakers' support for vaccine mandates.[3] Did the unique circumstances of the pandemic give rise to these partisan outcomes, or was immunization already a polarized issue?

We define "polarization" as an alignment of partisan identity with particular policy positions. Scholars have given attention to such partisan alignments on public health policy,[4,5] often with warnings that health policymaking is most likely to advance population health when it remains free of partisan politics.[6,7] Difficulties related to managing the COVID-19 pandemic support those claims.[1,8,9] When it comes to childhood immunizations, evidence suggests state policies have a strong effect on rates of vaccination and disease.[6,10,11] Therefore, it is especially important to examine polarization among those making these important policy decisions.

Goldstein et al.[12] examined immunization bills proposed in state legislatures from 2011 to 2017 and found that Republicans were more likely to sponsor "antivaccination" bills. Their analysis was limited to exemption bills and does not account for important political and epidemiological occurrences since 2017 (e.g., the majority of Trump's presidency, measles outbreaks in 2019). We build on their work by examining a broader spectrum of childhood vaccine bills over a much longer period (1995–2020). This allows us to address 3 specific questions: (1) Have childhood vaccination policies become more polarized over time? (2) Are some types of vaccination bills more polarized? (3) What is the relationship between polarization and the likelihood of a bill passing into law?

Our study period encompasses significant episodes in the history of US immunization policy, including the autism–mercury controversy, the politicized rollout of the human papillomavirus (HPV) vaccine, and the resurgence of measles.[6,13,14] Although childhood immunization laws have historically enjoyed widespread support across party lines,[15] organized campaigns to "green our vaccines" or to oppose HPV mandates on the basis of concerns about sexual promiscuity[14] could resonate more with the ideological commitments of the political left or right. Thus, the emergence and decline of these conflicts could produce changes in polarization over time.

Recent public opinion[16] as well as academic research on policymakers,[12] health communication,[17] and vaccine exemptions[18] indicate a correlation between vaccine opposition and political conservativism. Importantly, vaccine opposition is increasingly framed as an issue of civil liberties.[17] Thus, lawmakers may take positions based on partisan ideologies concerning state authority and parental rights[14,19] rather than on scientific recommendations or safety concerns. Certain bills could be more likely to trigger these ideological differences, such as those that target parents, modify vaccine mandates, or adjust public health authority during outbreaks.

To address these questions, we used sponsorship data on 1497 bills and voting returns for 228 legislative votes to create 2 separate measures of polarization: sponsor polarization and vote polarization. The first allowed us to view changes in polarization over a longer period; the second allowed us to compare polarization levels on immunization with 2 issues commonly considered more and less polarized (abortion and veterans' affairs).