Objectives: Reducing influenza infection among hospital employees is vital to prevent the spread of this infection among patients. A questionnaire study was performed to investigate seasonal influenza infection and vaccination among hospital employees, with the aim of decreasing the incidence of influenza. Methods: From 2014 to 2017, we distributed a questionnaire to hospital employees who were eligible for vaccination. The following information was collected: age of respondents, whether they lived with children aged <15 years, their preseason vaccination status, and their history of seasonal influenza infection. The data were analyzed and averaged for all 4 influenza seasons. Results: The incidence of influenza was 6.2% among employees through 4 seasons. The inoculation rate of the influenza vaccine ranged from 92% to 99%. The odds ratio for influenza infection among employees living with children aged <15 years was 2.19 (P<0.0001). A decrease in influenza infection was not observed in vaccinated employees (P=0.75). Conclusions: The results suggested that influenza infection in hospital personnel is not due to a low vaccination rate. Among people living with children younger than 15 years, the odds ratio of influenza infection was 2.19 (P<0.0001). These findings suggest that protection against influenza infection at home is particularly required for hospital employees living with children aged <15 years.