The COVID-19 green certificate's effect on vaccine uptake in French and Italian regions.

The COVID-19 green certificates were introduced in many countries in 2021 to encourage vaccine uptake against the COVID-19 virus in order to reduce the spread of severe infection among the population, ensure the safety of cross-border movements, and facilitate the resumption of social life and economic activities. This study uses a single-group interrupted time series approach to examine the effect of the green certificate announcement on the first doses of the COVID-19 vaccine in 20 Italian and 18 French regions during the summer of 2021. The estimation results show that the green certificate announcement mitigated regional disparities in vaccine uptake. It persuaded undecided people to have their first doses of the COVID-19 vaccine, especially in regions lagging in the mass vaccination campaign. It was less effective in those regions where there was already a high level of vaccine protection. The announcement also proved to be an effective political strategy with which to increase the first-dose rates immediately, but not in the long term.