Effectiveness of mRNA Vaccine Booster against SARS-CoV-2 Infection and COVID-19 in the Adult Population during the First Three Months of the Omicron Wave in Sicily.

This study confirmed the remarkable efficacy profile of the SARS-CoV-2 vaccine booster dose against infection, severe disease, and death attributable to the virus. Overall, the results of this study provide important real-world data to support the continued roll-out of the COVID-19 booster dose and have the potential to inform public health policy and guide decisions on vaccination strategies in countries around the world.