CAPE TOWN, South Africa. A groundbreaking study has revealed that twice-yearly injections have achieved 100% effectiveness in preventing new HIV infections among women, marking a significant breakthrough in the fight against the virus. The results were published Wednesday in the New England Journal of Medicine and discussed at an AIDS conference in Munich.

The study, conducted with around 5,000 participants in South Africa and Uganda, found that none of the young women and girls receiving the injections contracted HIV. In contrast, about 2% of those on daily prevention pills became infected. “To see this level of protection is stunning,” commented Salim Abdool Karim, director of an AIDS research center in Durban, South Africa, who was not involved in the research.

The injections, branded as Sunlenca and manufactured by U.S. drugmaker Gilead, are currently approved for HIV treatment in the U.S., Canada, Europe, and other regions. Gilead has yet to seek approval for using Sunlenca as a preventive measure, pending further testing in men.

The study’s unexpectedly promising results led to its early termination, with all participants now offered the injections, also known as lenacapavir. Thandeka Nkosi, who managed the Gilead research at the Desmond Tutu Health Foundation in Masiphumelele, South Africa, described the development as “quite revolutionary” for patients, noting that it “eliminates the whole stigma around taking pills” to prevent HIV.

Despite the enthusiasm surrounding the Sunlenca shots, concerns have been raised about the drug’s affordability. Gilead has not yet set a price for the prevention regimen but has indicated that it will pursue a “voluntary licensing program” that may limit the number of generic manufacturers allowed to produce it.

Winnie Byanyima, executive director of the U.N. AIDS agency, urged Gilead to collaborate with a U.N.-backed program to facilitate broader access to affordable versions of Sunlenca. “Gilead has a tool that could change the trajectory of the HIV epidemic,” she stated. The drug costs more than $40,000 annually in the U.S., though prices vary.

Dr. Helen Bygrave of Doctors Without Borders emphasized the potential impact of Sunlenca, stating that it could “reverse the epidemic if it is made available in the countries with the highest rate of new infections.” She called on Gilead to set a reasonable price to ensure accessibility in all countries.

Gilead has yet to announce the cost for prevention in lower-income nations but acknowledged the urgency of making Sunlenca available swiftly. Dr. Jared Baeten, Gilead’s senior vice president of clinical development, assured that the company is in discussions with generic manufacturers to expedite the process.

Currently, another HIV prevention shot, Apretude, is approved in some countries, including parts of Africa, but remains too expensive for most developing nations at approximately $180 per year.

UNAIDS reports a decline in global HIV infections in 2023, marking the lowest numbers since the late 1980s. However, HIV rates are rising in Eastern Europe, Latin America, and the Middle East. Andrew Hill from the University of Liverpool estimates that expanding Sunlenca production to treat 10 million people could reduce the price to about $40 per treatment, highlighting the urgent need for accessible prevention methods.

Hill described the Sunlenca shots as “about as close as you can get to an HIV vaccine,” underscoring their potential to significantly impact global HIV prevention efforts.