SARS-CoV-2 Vaccination and Protection Against Clinical Disease: A Retrospective Study, Bouches-du-Rhône District, Southern France, 2021

Pierre-Edouard Fournier (1, 2) , Linda Houhamdi (2) , Philippe Colson (2, 3) , Sébastien Cortaredona (2, 1) , Lea Delorme (2) , Carole Cassagne (2, 1) , Jean-Christophe Lagier (2, 3) , Hervé Chaudet (2, 1) , Hervé Tissot-Dupont (2, 1) , Audrey Giraud-Gatineau (2, 1) , Florence Fenollar (2, 1) , Matthieu Million (2, 3) , Didier Raoult (2, 3)

1 VITROME - Vecteurs - Infections tropicales et méditerranéennes
2 IHU Marseille - Institut Hospitalier Universitaire Méditerranée Infection
3 MEPHI - Microbes évolution phylogénie et infections

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.

Mots clés: COVID-19; SARS-CoV-2; vaccine; death; intensive care; hospitalization; protective effect

Domaines: Bactériologie; Cardiologie et système cardiovasculaire; Maladies émergentes; Maladies infectieuses; Parasitologie; Virologie

Pierre-Edouard Fournier, Linda Houhamdi, Philippe Colson, Sébastien Cortaredona, Lea Delorme, et al.. SARS-CoV-2 Vaccination and Protection Against Clinical Disease: A Retrospective Study, Bouches-du-Rhône District, Southern France, 2021. Frontiers in Microbiology, 2022, 12, ⟨10.3389/fmicb.2021.796807⟩. ⟨hal-03663493⟩