COVID-19 Vaccination and Rates of Infections, Hospitalizations, ICU Admissions, and Deaths in the European Economic Area during Autumn 2021 Wave of SARS-CoV-2.

The COVID-19 vaccination campaigns were met with a varying level of vaccine hesitancy in Europe. We analyzed the potential relationships between COVID-19 vaccine coverage in different countries of the European Economic Area and rates of infection, hospitalizations, admissions to intensive care units (ICU), and deaths during the autumn 2021 SARS-CoV-2 wave (September-December). Significant negative correlations between infection rates and the percentage of fully vaccinated individuals were found during September, October, and November, but not December. The loss of this protective effect in December is likely due to the emergence of the omicron (B.1.1.529) variant, better adapted to evade vaccine-induced humoral immunity. For every considered month, the negative linear associations between the vaccine coverage and mean number of hospitalizations (r= -0.61 to -0.88), the mean number of ICU admissions (r= -0.62 to -0.81), and death rate (r= -0.64 to -0.84) were observed. The results highlight that vaccines provided significant benefits during autumn 2021. The vaccination of unvaccinated individuals should remain the primary strategy to decrease the hospital overloads, severe consequences of COVID-19, and deaths.