SARS-CoV-2 vaccination and protection against clinical disease : a retrospective study, Bouches-du-Rhone District, Southern France, 2021 Fournier, P. E. Houhamdi, L. Colson, P. /Cortaredona, Sébastien Delorme, L. Cassagne, C. Lagier, J. C. Chaudet, H. Tissot-Dupont, H. Giraud-Gatineau, A. Fenollar, F. Million, M. Raoult, D. COVID-19 SARS-CoV-2 vaccine death intensive care hospitalization protective effect From January 18th to August 13th, 2021, 13,804 unvaccinated and 1,156 patients who had received at least one COVID-19 vaccine dose were tested qPCR-positive for SARS-CoV-2 in our center. Among vaccinated patients, 949, 205 and 2 had received a single, two or three vaccine doses, respectively. Most patients (80.3%) had received the Pfizer-BioNTech vaccine. The SARS-CoV-2 variants infecting vaccinated patients varied over time, reflecting those circulating in the Marseille area, with a predominance of the Marseille-4/20A.EU2 variant from weeks 3 to 6, of the Alpha/20I variant from weeks 7 to 25, and of the Delta/21A variant from week 26. SARS-CoV-2 infection was significantly more likely to occur in the first 13 days post-vaccine injection in those who received a single dose (48.9%) than two doses (27.4%, p< 10(-3)). Among 161 patients considered as fully vaccinated, i.e., >14 days after the completion of the vaccinal scheme (one dose for Johnson and Johnson and two doses for Pfizer/BioNTech, Moderna and Sputnik vaccines), 10 (6.2%) required hospitalization and four (2.5%) died. Risks of complications increased with age in a nonlinear pattern, with a first breakpoint at 54, 33, and 53 years for death, transfer to ICU, and hospitalization, respectively. Among patients infected by the Delta/21A or Alpha/20I variants, partial or complete vaccination exhibited a protective effect with a risk divided by 3.1 for mortality in patients >= 55 years, by 2.8 for ICU transfer in patients >= 34 years, and by 1.8 for hospitalization in patients >= 54 years. Compared to partial vaccination, complete vaccination provided an even stronger protective effect, confirming effectiveness to prevent severe forms of COVID-19. 2022 text https://www.documentation.ird.fr/hor/fdi:010084244 fdi:010084244 Fournier P. E., Houhamdi L., Colson P., Cortaredona Sébastien, Delorme L., Cassagne C., Lagier J. C., Chaudet H., Tissot-Dupont H., Giraud-Gatineau A., Fenollar F., Million M., Raoult D.. SARS-CoV-2 vaccination and protection against clinical disease : a retrospective study, Bouches-du-Rhone District, Southern France, 2021. 2022, 12, 796807 [10 ] EN FRANCE