Bouhnik Anne-Deborah, Preau Marie, Schiltz Marie-Ange, Lert France, Obadia Yolande, Spire Bruno. Unprotected sex in regular partnerships among homosexual men living with HIV: a comparison between sero-nonconcordant and seroconcordant couples (ANRS-EN12-VESPA Study). AIDS. Official journal of the international AIDS Society. 2007;21.