HIV prevention may only require two injections per year

Zero: That’s the number of new HIV infections among young women and adolescent girls who took a twice-yearly preventive medicine.

Researchers tested a new formulation of pre-exposure prophylaxis, or PrEP, in a clinical trial of HIV-negative cisgender women and teens ages 16 to 25 in South Africa and Uganda. The Phase III trial compared a twice-yearly injection of the antiviral drug lenacapavir to a widely used daily PrEP pill that contains two different antiviral drugs.

There were no new infections among the more than 2,100 women and girls who received twice-yearly lenacapavir, researchers from the pharmaceutical company Gilead Sciences report online July 24 in the New England Journal of Medicine. There were 16 new infections among the close to 1,100 taking the daily PrEP pill Truvada, the first-ever PrEP option, which became available in 2012. The trial results were also presented July 24 at the 2024 International AIDS Conference in Munich.

Young women and adolescent girls from sub-Saharan Africa are among the groups at high risk for HIV infection. Of the 4,000 young women and adolescent girls ages 15 to 24 who became infected with HIV globally each week in 2023, on average, around 75 percent were from sub-Saharan Africa, according to The Joint United Nations Programme on HIV/AIDS.

Studies have found that young women and teens are open to PrEP but that there are barriers to using the preventive medicine. The stigma surrounding HIV casts a shadow on PrEP. Some women fear that in taking the drugs others will assume they are HIV positive (SN: 12/1/20). And the daily pill regimen can be difficult to continue.

“PrEP use, especially ongoing and consistent use, is challenged by HIV-related stigma from partners, peers and community, limited understanding or acceptance of one’s own risk and imperfect provider knowledge and communication,” says Amrita Rao, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health who was not involved in the new study. The twice-yearly shot may make it easier to maintain protection, she says.

In 2021, the U.S. Food and Drug Administration approved an every-other-month injectable PrEP, a shot of the antiviral drug cabotegravir. But the prohibitive cost has so far kept it off the table for low- and middle-income countries. This year, the U.S. President’s Emergency Plan for AIDS Relief supplied the cabotegravir PrEP shot to Malawi, Zambia and Zimbabwe.

The twice-yearly injection may mean easier adherence and fewer clinic visits, Rao says, but the trade-off may be reduced testing and counseling opportunities for patients. “Having an additional choice and the ability to select the method that is best for you, however, is a welcome advance.”

But “a recurring theme of PrEP rollout has been long delays between drug approval and real-world delivery to those with the greatest need,” Rao says. Without thought given to the implementation of the twice-yearly shot, “even this incredibly promising tool may not realize its full benefit.”