Abstract : Objective: The objective is to study the contribution of vaccination against COVID-19 in elderly subjects infected with COVID-19. Method: a retrospective study with screening of medical records was carried out among patients affected by an infection linked to COVID-19 during the 5th epidemic wave that required admission in a French hospital. Results: 51 subjects were included, with 25 women (49 %), mean age 85 y+/-6 years. Among the 51 patients, 28 patients were hospitalized specifically for the management of COVID-19 infection and 25 (49 %) patients showed signs of severity on admission; 35 patients (68.6 %) were vaccinated, with a complete vaccination schedule (2 doses). We noted 16 deaths (31.4 %). Oxygen saturation on admission was significantly associated with the rates of COVID lesions on chest CT (p = 0.018), yet the correlation remained moderate. Vaccination had a significant protective effect on patient death (p = 0.0236). Conclusion: Vaccination is more than ever the only weapon of prevention against serious complications related to COVID-19 infection, especially in very elderly subjects, exposed to several comorbidities and polymedication. Prevention efforts and dedicated health explanations are the keys to a useful vaccination being targeted on elderly populations at risk.