Risk of SARS-CoV-2 infection and subsequent hospital admission and death at different time intervals since first dose of COVID-19 vaccine administration, Italy, 27 December 2020 to mid-April 2021
Alberto Mateo‐Urdiales, Stefania Spila Alegiani, Massimo Fabiani, Patrizio Pezzotti, Antonietta Filia, Marco Massari, Flavia Riccardo, Marco Tallon, Valeria Proietti, Martina Del Manso, Maria Puopolo, Matteo Spuri, Cristina Morciano, Fortunato D’Ancona, Roberto Da, Serena Battilomo, Antonino Bella, Francesca Menniti‐Ippolito, on behalf of the Italian Integrated Surveillance of COVID-19 study group, on behalf of the Italian COVID-19 vaccines registry
Abstract
To assess the real-world impact of vaccines on COVID-19 related outcomes, we analysed data from over 7 million recipients of at least one COVID-19 vaccine dose in Italy. Taking 0-14 days post-first dose as reference, the SARS-CoV-2 infection risk subsequently decreased, reaching a reduction by 78% (incidence rate ratios (IRR): 0.22; 95% CI: 0.21-0.24) 43-49 days post-first dose. Similarly, hospitalisation and death risks decreased, with 89% (IRR: 0.11; 95% CI: 0.09-0.15) and 93% (IRR: 0.07; 95% CI: 0.04-0.11) reductions 36-42 days post-first dose. Our results support ongoing vaccination campaigns.