Indoor Vaccine Mandates in US Cities, Vaccination Behavior, and COVID-19 Outcomes

Many US cities implemented indoor vaccine mandates to incentivize citizens to get vaccinated and reduce the spread of COVID-19. Previous research finds that similar country-level mandates increased vaccine uptake substantially. However, with city-level mandates, unvaccinated individuals could easily travel to neighboring cities without the mandate, whereas it is difficult to travel across country. Thus, the effects of indoor vaccine mandates implemented in US cities on individuals’ decisions to get vaccinated may differ from country-level mandates. This paper offers the first analysis of the effects of city-level indoor vaccine mandates. Using the synthetic difference-indifferences approach, we find that these mandates had no significant effect on COVID-19 cases, deaths, or vaccine uptake in any of the cities. We also compare our findings to the synthetic control and the difference-in-differences estimates and find the same result. Our findings put into question the efficacy of city-level vaccine mandates