The current new coronavirus pandemic has highlighted the importance of taking into consideration population groups particularly at risk of contracting Covid-19 disease or developing severe forms of the disease. The medical literature, the press and the authorities have thus stepped up the use of the expression « vulnerable populations » in recent weeks to refer to it. However, behind this general expression there are diverse but often interdependent realities whose specific consideration and understanding seem essential for the effective management of the epidemic and its health and socio-economic consequences.