- Post-exposure prophylaxis for HIV is primarily used following high-risk sexual contact and after accidental exposure to blood among healthcare workers. - Excessively long delays in seeking medical consultation following sexual exposure. - Difficulties in following up with patients after the initial prescription of prophylaxis. - Post-exposure prophylaxis, as prescribed between 1999 and 2003, was not "cost-effective," due in particular to numerous prescriptions following sexual intercourse with a partner of unknown HIV status.