Prioritization preferences for COVID-19 vaccination are consistent across five countries

The rapid development and initial rollout of COVID-19 vaccines presented unprecedented logistical and ethical challenges. Limited vaccine supplies necessitated the establishment of prioritization criteria by national policymakers, focusing on factors like age, health conditions, and occupation. This study investigates public preferences for vaccine allocation to understand how these align with, or deviate from, official guidelines. Public support for prioritization policies is crucial for effective pandemic response and overcoming vaccine hesitancy. Understanding the gap between public preferences and policies enhances the effectiveness of decision-making and promotes the legitimacy of these choices. The research employs a survey administered in five countries (Brazil, Germany, Italy, Poland, and the U.S.) between September and December 2020, involving 4366 respondents. Data was collected using a ranking task and a conjoint experiment. The ranking task required respondents to rank eight groups based on vaccination priority, while the conjoint experiment presented pairs of fictional individuals with varying attributes for prioritization decisions. This two-pronged approach allowed for a comprehensive analysis of public preferences, contrasting utilitarian and deservingness heuristics.

Existing research on vaccine prioritization preferences exhibits a growing body of work focusing on both global distribution preferences (prioritizing Global South vs. Global North) and within-country prioritization preferences. Studies using ranking tasks and forced-choice experiments consistently reveal public support for prioritizing the elderly, frontline healthcare workers, and individuals with pre-existing conditions. However, non-utilitarian factors also influence preferences, including compliance behavior, lifestyle choices, and even discriminatory tendencies based on ethnicity or citizenship. This study builds upon this existing literature by providing additional cross-national evidence, employing multiple methodological approaches, and examining attributes such as elite group membership, citizenship, parenthood, and the first-come, first-served principle.

The study employed a cross-national survey design, recruiting 4366 participants from Brazil, Germany, Italy, Poland, and the United States via a commercial access panel. Quotas were used to ensure the sample approximated age, gender, and education distributions within each country's adult population. Data collection occurred between September and December 2020, before widespread vaccine rollout. Two primary methods were utilized to elicit vaccine prioritization preferences: a ranking task and a conjoint experiment. The ranking task presented eight groups (varying by age, profession, and health status) for respondents to rank in order of vaccination priority. Groups included healthcare workers, politicians, athletes, business leaders, individuals with pre-existing conditions, children, and the elderly. The groups were designed based on expert proposals for prioritization principles, including minimizing severe COVID-19 cases, protecting high-risk workers, preventing transmission within vulnerable groups, and maintaining public life and government effectiveness. The conjoint experiment presented participants with pairs of hypothetical individuals with randomly varied attributes (gender, age, children, occupation, citizenship, pre-existing condition, and early registration). Respondents chose which individual in each pair should be prioritized. This approach allowed for the isolation of individual attribute effects. Individual-level covariates (age, gender, children, political ideology, and pre-existing health conditions) were collected for subgroup analyses to assess preference heterogeneity. Data analysis involved calculating average priority rankings for the ranking task and estimating marginal means, average marginal component effects (AMCE), and average marginal interaction component effects (AMICE) using linear regression models for the conjoint experiment. Random forest analysis assessed attribute importance in the conjoint experiment, while open-ended questions provided additional insight into respondent reasoning.

Results across both the ranking task and the conjoint experiment revealed striking consistency in prioritization preferences across the five countries. Healthcare workers consistently ranked highest, followed by individuals with medical preconditions and the elderly. These findings align with both utilitarian principles and expert guidelines. However, the study also identified non-utilitarian factors influencing prioritization. Early vaccine registration significantly increased the likelihood of prioritization, reflecting a 'first-come, first-served' heuristic. Citizenship status also played a role, with citizens generally prioritized over non-citizens, indicating health-care chauvinism. While less pronounced, parents were also favored over non-parents. Analysis of attribute importance using random forests confirmed the prominence of healthcare profession and pre-existing health conditions in respondents' decisions. Subgroup analyses revealed minimal preference heterogeneity based on respondents' demographic characteristics or political ideology, suggesting a relatively coherent understanding of prioritization across different segments of the populations studied. A slight exception was observed regarding right-leaning participants who showed a higher preference for citizens over non-citizens, compared to left-leaning individuals. However, even this effect had limited impact on the overall consistency of prioritization preferences.

The study's findings demonstrate a substantial alignment between public preferences for COVID-19 vaccine prioritization and early expert guidelines. The strong consensus across countries and demographic groups regarding the prioritization of high-risk individuals and essential workers highlights a potential avenue for policymakers to build public trust and acceptance of vaccination programs. The results confirm that prioritizing those most likely to experience severe illness and those crucial for pandemic mitigation resonates with the public. The identification of non-utilitarian factors such as 'first-come, first-served' and citizenship bias, however, reveals areas where public opinion deviates from ethical guidelines. This highlights the complex interplay between utilitarian and non-utilitarian considerations shaping public preferences. The relatively low level of preference heterogeneity within countries strengthens the study's findings, indicating a broad agreement on core prioritization principles. Further research could explore the specific mechanisms driving these non-utilitarian preferences, examining the influence of media representations, social networks, and cultural norms.

This cross-national study reveals a surprising level of consistency in public preferences regarding COVID-19 vaccine prioritization. While the public largely agrees with expert guidelines in prioritizing healthcare workers and high-risk individuals, the study also underscores non-utilitarian influences, such as a 'first-come, first-served' approach and biases toward citizens. These findings provide valuable insights for policymakers in designing equitable and effective vaccination programs, balancing public preferences with ethical considerations and fundamental human rights.

The study's reliance on an online access panel might limit the generalizability of the findings to the broader population. Social desirability bias could also influence responses, although the study's design attempts to mitigate this effect. The study does not address actual prioritization practices by healthcare providers, so it cannot comment on discriminatory allocation of vaccines in practice. Finally, while the findings suggest strong cross-national consistency, the specific cultural contexts of the five sampled nations might influence responses differently, meaning that these results cannot be universally generalized.