I n global health, true breakthroughs are rare. When they come, their value is measured not in laboratories , but in the lives they save. Today, that test centres on lenacapavir – sometimes called Len – a long-acting HIV prevention drug that could transform the global epidemic , particularly for adolescent girls and young women , who remain at its heart. Across sub-Saharan Africa , adolescent girls and young women continue to face a disproportionate risk of HIV infection. Gender inequality, stigma, and the lack of control over their own health choices mean that many existing prevention tools do not reach them effectively. Daily oral Pre-Exposure Prophylaxis (PrEP), a similar HIV prevention drug, has delivered strong results in some key populations. But for many women and girls, adherence can be hard because of scrutiny at home, fear of stigma, and the reality of changing routines, school, travel, and other competing demands. Len changes that equation.…