Introduction: In early February 2007, the coordinating physician at a nursing home reported a significant number of flu-like illnesses among residents and staff. Methods: A cohort study was conducted among all residents and staff. Rapid influenza tests were performed. Demographic, geographic, and medical information was collected from residents’ medical records or through the administration. A descriptive analysis was performed, and factors associated with the onset of the illness were investigated. Results: The attack rate during the outbreak was 48% among residents and 26% among staff. Influenza was confirmed in two residents. Influenza vaccination coverage among residents was 65%. No staff members were vaccinated. The outbreak was not reported to the authorities until the 9th day, leading to the implementation of the first control measures. The attack rate was three times higher in one of the two living areas, which was affected first and housed more vulnerable residents. Discussion: Incomplete vaccination of residents and staff, staff involvement in transmission, delayed reporting, and the proximity of frail individuals in a communal setting likely contributed to the onset and spread of the outbreak, underscoring the importance of adhering to existing guidelines.