IMPORTANCE Coronavirus disease 2019 (COVID-19) is a major threat to nursing homes. During the COVID-19 pandemic wave that hit France in March and April 2020, staff members of some French nursing homes decided to confine themselves with their residents on a voluntary basis to reduce the risk of entry of the severe acute respiratory syndrome coronavirus 2 into the facility. OBJECTIVE To investigate COVID-19-related outcomes in French nursing homes that implemented voluntary staff confinement with residents. DESIGN, SETTING, AND PARTICIPANTS This retrospective cohort study was conducted in French nursing homes from March 1 to May 11, 2020. Participants included residents and staff members of the nursing homes where staff participated in voluntary self-confinement as well as those of the facilities for elderly people where staff did not practice self-confinement. Rates of COVID-19 cases and mortality in the cohort of nursing homes with self confinement were compared with those derived from a population-based survey of nursing homes conducted by French health authorities. EXPOSURES Nursing homes with staff who self-confined were identified from the media and included if the confinement period of staff with residents was longer than 7 days. MAIN OUTCOMES AND MEASURES Mortality related to COVID-19 among residents and COVID-19 cases among residents and staff members. COVID-19 was diagnosed by primary care or hospital physicians on the basis of fever and respiratory signs (eg, cough, dyspnea) or a clinical illness compatible with COVID-19; COVID-19 diagnoses were considered confirmed if real-time reverse transcriptase-polymerase chain reaction testing for severe acute respiratory syndrome coronavirus 2 on nasopharyngeal swab was positive and considered possible if the test had not been performed or results were negative. Cases of COVID-19 were recorded by a telephone interview with the directors of nursing homes with staff who self-confined and by a nationwide declaration survey to health authorities for all facilities. RESULTS This study included 17 nursing homes in which 794 staff members confined themselves to the facility with their 1250 residents. The national survey included 9513 facilities with 385 290 staff members and 695 060 residents. Only 1 nursing home with staff who self-confined (5.8%) had cases of COVID-19 among residents, compared with 4599 facilities in the national survey (48.3%) (P < .001). Five residents (0.4%) in the nursing homes with staff who self-confined had confirmed COVID-19, compared with 30 569 residents (4.4%) with confirmed COVID-19 in the national survey (P < .001); no residents of facilities with self-confinement had possible COVID-19, compared with 31 799 residents (4.6%) with possible COVID-19 in the national survey (P < .001). Five residents (0.4%) in the nursing homes with staff who self-confined died of COVID-19, compared with 12 516 (1.8%) in the national survey (odds ratio, 0.22; 95% CI, 0.09-0.53; P < .001). Twelve staff members (continued) Key Points Question Was self-confinemen...