During 2021-2022 many countries in the European region of the World Health Organization (WHO) adopted mandatory and incentive-based vaccination measures to stimulate immunization against COVID-19. The measures ranged from positive incentive-based programs (i.e., cash incentives, meal discounts, and lotteries) to introducing COVID-19 certificates and enforcing the universal mandatory vaccination with fines. We assessed the effect of such interventions on COVID-19 vaccine uptake in the population of eight countries within the region. An interrupted time series (ITS) analysis was performed using an autoregressive integrated moving average (ARIMA) approach to account for autocorrelation and seasonality. The results showed the immediate positive impact of vaccination incentives on vaccine uptake in most cases, with the highest impact being cash incentives for the population (1197 per million population per day). Discount incentives did not show any significant impact. The introduction of COVID-19 certificates was associated with a significant immediate or gradual increase in daily administered vaccine doses in all the countries included in the study, up to 117,617 doses gained per million per month. The effect of mandatory vaccination for all or some groups of the population varied from a continuous decrease in daily administered doses (332 per million capita per day), no significant effect, or a delayed or temporary increase (1489 per million capita per day).
Keywords: COVID-19; Europe; mandatory vaccination; vaccination policy; vaccine incentives; vaccine uptake.