Introduction
At HUG, healthcare workers (HCW) are currently obliged to be vaccinated or wear masks in ward corridors and patient rooms during seasonal influenza (SI) epidemics. Since winter 2011-12, HCWs vaccinated against SI wear a badge with the text "I am vaccinated to protect you" and, since winter 2012-13, those who are not vaccinated wear a badge with the text "I wear a mask to protect you". Regular audits have allowed to quantify compliance with recommendations in parallel with active recording of influenza cases.