Do Incentive Policies Improve COVID-19 Vaccination Rate in the U.S.? Evidence from a Longitudinal County-Level Analysis

Background and Purpose: Various public health policies have been implemented in states of the United States to improve the COVID-19 vaccination rate. Noticeably, policymakers have an increasing interest in financial incentives to improve the COVID-19 vaccination rates. In 2021, lottery policy and bonus incentive policy are the most common public health strategy adopted by the U.S. to stimulate the COVID-19 vaccination. More than 1,148 U.S. counties were impacted by COVID-19 vaccination incentive policies. Implementation of incentive policies requests considerable consumption of public finances and resources. Understanding factors associated with effective vaccination incentives is needed to inform future public policies for improving vaccination rates. This nationwide longitudinal study aims to 1) analyze the impact of COVID-19 vaccine incentive policies, including lottery incentives and bonus incentives, on county-level COVID-19 vaccination rates, and 2) examine the interactive effects between the COVID-19 vaccine incentive policies and socioeconomic factors on county-level COVID-19 vaccination rates.

Methods: This study is a longitudinal county-level analysis using secondary data from multiple data sources including the U.S. Centers for Disease Control and Prevention (CDC) COVID-19 Vaccine Tracker (COVID-19 vaccination rates), the National Government Association (incentive policies), and the U.S. Census (e.g., demographics, unemployment rate, per capita income). In measuring the various incentive policy programs, we coded the incentive policies into three categories: 1) no incentive policy; 2) bonus incentives, including providing food/entertainment vouchers and small cash; and 3) lottery incentives, including drawing for cash and/or scholarship. Five Pooled OLS regression model with random effects were developed to evaluate the effects of incentive policies (bonus incentives and lottery incentives) on COVID-19 vaccination rates and the interaction effects between incentive policies and socioeconomic factors (e.g., per capita income, unemployment rate, race, and education level).

Results: Both bonus incentive policies (R²= 2.23, p=0.00) and lottery incentive policies (R²= 1.34, p=0.00) were positively associated with COVID-19 vaccination rates. Compared to counties without any incentive policies, counties with bonus incentives have a 223.0% increase in COVID-19 vaccination rates, while counties with vaccine lottery incentives have a 134.3% increase in COVID-19 vaccination rates. However, the associations were divergent in the context of counties’ socioeconomic status. Effects of bonus policies and lottery policies on COVID-19 vaccination rates had upward trends with counties’ per capita income increase. General education level and unemployment rates raised the effects of bonus policies on COVID-19 vaccination rates, but reduced the effects of lottery policies. Rates of racial minorities moderated the positive effects of bonus policies and lottery policies on COVID-19 vaccination rates.

Conclusions: Our findings have important policy applicability and suggest that lottery-based incentives and bonus-based incentives can be effective at increasing vaccine uptake. In the design and implementation of incentives, police should consider the social-economic status of the county. Bonus incentives are more effective in counties with high per capita income and high general education levels. However, lottery incentives are more effective in counties with low unemployment rates and high percentages of BIPOC populations.