Thirumurthy, Harsha and Milkman, Katherine L. and Volpp, Kevin and Buttenheim, Alison and Pope, Devin G., Association between statewide financial incentive programs and COVID-19 vaccination rates (August 27, 2021). Available at SSRN: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3912786&download=yes
To encourage COVID-19 vaccination, many states in the US have introduced financial incentives ranging from small, guaranteed rewards to lotteries that give vaccinated individuals a chance to win $1 million or more. We compiled information on statewide incentive programs along with data on daily vaccine doses administered per 100,000 individuals in each state. Leveraging variation across states in the daily presence of incentives, we used difference-in-differences regressions to examine the association between these incentive program indicators and vaccination rates. Difference-in-differences analysis showed that 24 statewide incentive programs were associated with a non-significant relative decline in daily vaccination rates of 8.9 per 100,000 individuals (95% CI [-64.3,46.5]; p=0.75). Furthermore, there was no significant difference in vaccination trends between states with and without incentives in any of the 14 days before or after incentives were introduced. Lotteries and other incentives offered by 24 states were not associated with a significant change in COVID-19 vaccination rates. More substantial incentives or mandates may be necessary to raise vaccination rates.