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.