Fournier P. E. auteur aut IRD Houhamdi L. auteur aut IRD Colson P. auteur aut IRD Cortaredona Sébastien auteur aut IRD Delorme L. auteur aut IRD Cassagne C. auteur aut IRD Lagier J. C. auteur aut IRD Chaudet H. auteur aut IRD Tissot-Dupont H. auteur aut IRD Giraud-Gatineau A. auteur aut IRD Fenollar F. auteur aut IRD Million M. auteur aut IRD Raoult D. auteur aut IRD text journalArticle eng text/pdf reformatted digital access 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. specialized COVID-19 SARS-CoV-2 vaccine death intensive care hospitalization protective effect FRANCE 050 052 12 796807 [10 ] 2022 https://www.documentation.ird.fr/hor/fdi:010084244 10.3389/fmicb.2021.796807 [F B010084244] https://www.documentation.ird.fr/hor/fdi:010084244 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2022-03/010084244.pdf IRD - Base Horizon / Pleins textes 2022-03-09 2025-02-24 fdi:010084244 fre