HARARE, Zimbabwe — Young women, mothers holding babies and some men lined up in a dusty field on the outskirts of Zimbabwe’s capital, Harare. They came for injections of a new HIV prevention drug launched in the country on Thursday, one that only needs to be administered twice a year. Zimbabwe , where HIV has led to tens of thousands of deaths over the past two decades, is one of the first countries to roll out lenacapavir, a long-acting drug that authorities hope will slow new infections. With clinical studies demonstrating near-total protection , the drug has been described by some health officials as a turning point for high-risk groups. Others warn that turning scientific promise into broad impact will require overcoming funding constraints, infrastructure gaps and the challenge of keeping patients engaged. At the Zimbabwe launch, Constance Mukoloka stepped out of a mobile clinic, beaming with relief after receiving one of the first doses. “I am safe, I can work with confidence now,” said the 27-year-old sex worker, describing how daily preventive preexposure prophylaxis, or