BackgroundDuring the COVID-19 pandemic, the suspension of relatives’ visits was a common measure in healthcare facilities to prevent the spread of the virus among patients. This measure caused significant adverse consequences for hospitalized patients. Volunteers’ intervention was an alternative but could also lead to cross transmission events.Aimsin order to secure their intervention with patients, we implemented an infection control training to evaluate and to improve the knowledge of volunteers about infection control measures.MethodWe performed a before-after study in a group of five tertiary referral teaching hospitals in the suburbs of Paris. A total of 226 volunteers from three groups (religious representatives, civilian volunteers and users’ representatives) were included. Basic theoretical and practical knowledge about infection control, hand hygiene, and glove and mask use were evaluated just before and immediately after a three-hour training program. The contribution of the characteristics of the volunteers to the results was studied.FindingsThe initial conformity rate for theoretical and practical infection control measures ranged from 53% to 68%, depending on the participants’ activity status and education level. Some critical shortcomings in hand hygiene as well as mask and glove wearing putatively endangered the patients and volunteers. Surprisingly, serious gaps were also identified among volunteers who experienced care activities. Regardless of their origin, the program significantly improved both their theoretical and practical knowledge (p<0.001). Real-life observance and long-term sustainability should be monitored.ConclusionsTo become a secure alternative to relatives’ visits, volunteers’ interventions must be preceded by the assessment of their theoretical knowledge and practical skills in infection control. Additional study, including practice audit, must confirm the implementation of the acquired knowledge in the real-life.