BACKGROUND/OBJECTIVE: The COVID-19 epidemic is particularly serious in older adults. The symptomatology and epidemic profile remain little known in this population, especially in disabled oldest-old people with chronic diseases living in nursing homes. The objective of the present study was to comprehensively describe symptoms and chronological aspects of the diffusion of the SARS-CoV-2 virus in a nursing home, among both residents and caregivers. DESIGN: Five-week retrospective cohort study. SETTING: A middle-sized nursing home in Maine-et-Loire, west of France. PARTICIPANTS: Eighty-seven frail older residents (87.9 +/- 7.2years; 71 % female) and 92 staff members (38.3 +/- 11.7years; 89 % female) were included. MEASUREMENTS: Mass screening for SARS-CoV-2 was performed in both residents and staff. Attack rate, mortality rate, and symptoms among residents and staff infected with SARS-CoV-2 were recorded. RESULTS: The attack rate of COVID-19 was 47 % in residents (case fatality rate, 27 %), and 24 % in staff. Epidemic curves revealed that the epidemic started in residents before spreading to caregivers. Residents exhibited both general and respiratory signs (59 % hyperthermia, 49 % cough, 42 % polypnea) together with geriatric syndromes (15 % falls, 10 % altered consciousness). The classification tree revealed 100 % COVID-19 probability in the following groups: i) residents younger than 90 with dyspnea and falls; ii) residents older than 90 with anorexia; iii) residents older than 90 without anorexia but with altered consciousness. Finally, 41 % of staff members diagnosed with COVID-19 were asymptomatic. CONCLUSIONS: The pauci-symptomatic expression of COVID-19 in older residents, together with the high prevalence of asymptomatic forms in caregivers, justifies mass screening in nursing homes, possibly prioritizing residents with suggestive combinations of clinical signs including dyspnea, falls, anorexia and/or altered consciousness.