Conditional cash lotteries increase COVID-19 vaccination rates.

Conditional cash lotteries (CCLs) provide people with opportunities to win monetary prizes only if they make specific behavioral changes. We conduct a case study of Ohio's Vax-A-Million initiative, the first CCL targeting COVID-19 vaccinations. Forming a synthetic control from other states, we find that Ohios incentive scheme increases the vaccinated share of state population by 1.5 percent (0.7 pp), costing sixty-eight dollars per person persuaded to vaccinate. We show this causes significant reductions in COVID-19, preventing at least one infection for every six vaccinations that the lottery had successfully encouraged. These findings are promising for similar CCL public health initiatives.