  Covid-19 vaccination has posed crucial challenges to policymakers and health
administrations worldwide. In addition to the pressure posed by the pandemic,
government administration has to strive against vaccine hesitancy, which seems
to be considerably higher concerning previous vaccination rollouts. To increase
the vaccination protection of the population, Ohio announced a monetary
incentive as a lottery for those who decided to vaccinate. This first example
was followed by 18 other states, with varying results. In this paper, we want
to evaluate the effect of such policies within the potential outcome framework,
using the penalized synthetic control method. We treat with a panel dataset and
estimate causal effects at a disaggregated level in the context of staggered
treatment adoption. We focused on policy outcomes at the county, state, and
supra-state levels, highlighting differences between counties with different
social characteristics and time frames for policy introduction. We also studied
the nature of the treatment effect to see whether the impact of these monetary
incentives was permanent or only temporary, accelerating the vaccination of
citizens who would have been vaccinated in any case.
