The effect of COVID certificates on vaccine uptake, health outcomes, and the economy.

In the COVID-19 pandemic many countries required COVID certificates, proving vaccination, recovery, or a recent negative test, to access public and private venues. We estimate their effect on vaccine uptake for France, Germany, and Italy using counterfactuals constructed via innovation diffusion theory. The announcement of COVID certificates during summer 2021 were associated - although causality cannot be directly inferred - with increased vaccine uptake in France of 13.0 (95% CI 9.7-14.9) percentage points (p.p.) of the total population until the end of the year, in Germany 6.2 (2.6-6.9) p.p., and in Italy 9.7 (5.4-12.3) p.p. Based on these estimates, an additional 3979 (3453-4298) deaths in France, 1133 (-312-1358) in Germany, and 1331 (502-1794) in Italy were averted; and gross domestic product (GDP) losses of €6.0 (5.9-6.1) billion in France, €1.4 (1.3-1.5) billion in Germany, and €2.1 (2.0-2.2) billion in Italy were prevented. Notably, in France, the application of COVID certificates averted high intensive care unit occupancy levels where prior lockdowns were instated.