In the PURPOSE 1 phase 3 trial in South Africa and Uganda, no HIV infections occurred among 2,134 participants assigned to twice-yearly lenacapavir injections. The result suggests long-acting prevention could help people for whom daily pills are difficult, while broader research and accessible delivery remain essential.
TLDR: A major trial in South Africa and Uganda recorded no HIV infections among participants assigned to twice-yearly lenacapavir injections. The drug may offer a less frequent alternative to daily prevention pills, but expanded research, safety monitoring, affordable supply, and accessible clinical services will shape its public-health impact.
A twice-yearly injection of the HIV drug lenacapavir prevented new infections among participants in a large clinical trial in South Africa and Uganda, researchers reported in 2024. No infections occurred in the group receiving the injections, a result that has drawn attention to a prevention approach requiring far fewer doses than existing options.
The phase 3 PURPOSE 1 trial enrolled 5,338 adolescent girls and young women. Participants were assigned to receive injections of lenacapavir, daily oral pre-exposure prophylaxis (PrEP) using emtricitabine and tenofovir disoproxil fumarate, or daily emtricitabine and tenofovir alafenamide. The study was conducted in areas where young women face substantial HIV risk and where taking a daily pill can be difficult for many reasons.
Among 2,134 participants assigned to lenacapavir, researchers recorded no HIV infections during the primary analysis period. In the group assigned to the daily emtricitabine-tenofovir disoproxil fumarate pill, 16 infections occurred; in the emtricitabine-tenofovir alafenamide group, 39 occurred. The rate in the lenacapavir group was significantly lower than the estimated background rate among women in the study communities.
Lenacapavir is a capsid inhibitor, a drug that interferes with the protein shell surrounding HIV’s genetic material. Gilead Sciences developed the medicine. For prevention in this trial, participants received two injections under the skin every six months, along with oral doses at the start of treatment. The long interval between injections could make prevention more practical for people who find daily medication burdensome or difficult to keep private.
The findings, presented at the International AIDS Conference and published in the New England Journal of Medicine, do not mean that the shot will work equally well in every population or setting. The trial involved adolescent girls and young women in two countries, and its results speak directly to that group. Researchers will need evidence from additional studies to understand effectiveness, safety, and access for other populations, including men and transgender people.
The study also measured infections among participants receiving daily PrEP. Those results should not be read as evidence that daily pills are ineffective: oral PrEP is highly protective when taken consistently. Rather, the trial highlighted a persistent challenge in real-world prevention. A medication can work biologically yet offer less protection if people cannot or do not take it regularly. Longer-acting options may help address that gap, though they still require clinic visits and reliable follow-up.
Safety monitoring found that injection-site reactions were more common with lenacapavir than with the oral regimens. Most reported reactions were mild or moderate, but some participants developed lumps where the injections were given. As with any prevention medicine, informed choice matters: people need clear information about benefits, side effects, alternatives, and the importance of HIV testing before and during use. Regular testing is necessary because lenacapavir is not a treatment for an infection that has already occurred.
The results came from a company-sponsored trial, with Gilead involved in its design and analysis. Independent review and publication in a peer-reviewed journal make the data available for scrutiny, while further research and public-health monitoring will help clarify how well the approach performs outside the trial. Researchers are also studying lenacapavir for HIV prevention in other populations and examining how best to deliver it.
The trial offers evidence that a long-acting medicine can sharply reduce the burden of HIV prevention for young women at high risk. Turning that promise into population-level impact will depend on affordability, dependable supply, accessible clinics, and whether communities want the injection. The next steps include regulatory review, implementation studies, and continued monitoring of safety and effectiveness as use expands.
Susan Carter serves as a Senior Correspondent for Just Right News, where she leads the network’s comprehensive coverage of Health, Medicine, and Public Policy. With a career dedicated to dissecting the complexities of the American healthcare system, Susan brings a principled perspective to the most pressing debates of the day. Her reporting is characterized by a commitment to individual liberty, fiscal responsibility, and a healthy skepticism of government overreach, making her a vital voice for audiences seeking clarity in an increasingly regulated landscape.
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