The two injections a year that could eradicate HIV: the treatment that the US and Europe have just approved is still being studied.

Despite decades of progress, HIV still infects more than a million people a year worldwide, with 3,000 new diagnoses annually in Spain , and a vaccine remains a pipe dream. But last year, the world caught a glimpse of what could be the next best thing: an injectable drug that provides six months of protection with each injection . An innovation that earned it the title of "Scientific Breakthrough of the Year 2024" from the prestigious scientific journal Science .

We're talking about Lenacapavir, an innovative therapy developed after more than 16 years of research and the analysis of more than 4,000 molecules, which promises to transform HIV prevention with nearly 100% efficacy. Its mechanism of action blocks the viral capsid, preventing both its entry into and exit from cells, making it a vital tool in the fight against HIV.

One of the most notable features is its biannual subcutaneous injection , a significant advantage over the currently available pre-exposure prophylaxis (PrEP) treatment option, which requires daily doses. These two injections per year significantly improve treatment adherence, a major barrier to HIV prevention.

Until now, Lenacapavir was used residually as a rescue therapy for HIV patients for whom other treatments failed. But this Wednesday, the US FDA approved its injection twice a year as a preventive measure against the disease , an approval also being considered by the European Medicines Agency (EMA). This way, the therapy can be injected into people who are not infected but are in high-risk environments.

For experts, the FDA approval, and the expected October approval by the EMA , represent an opportunity to achieve the end of HIV. This is due to the nearly 100% effectiveness demonstrated in studies, and because its biannual administration via subcutaneous injection exponentially improves adherence to PrEP.

"If you had the entire at-risk population take this treatment, HIV would disappear."

For Robert Güerri , head of the Infectious Diseases Service at Hospital del Mar, its approval in Europe as a preventive tool would be "a complete game changer."

“This drug is interesting for several reasons, as it radically changes the way we treat the disease. Currently, HIV prevention is pharmacological and is carried out with a drug called Truvada. It's a PrEP therapy where you have to take the medication every day to avoid infection. Lenacapavir radically changes all of this, because with just two doses a year, you are permanently protected, which guarantees greater effectiveness, and I say this from experience. We run a PrEP clinic with Truvada and have had experiences where infections occur despite this, because we know the reality is that the treatment is not taken 100% as it should be, because people often forget. But with the new drug, this won't happen because with a single dose, you are already protected for months,” the infectious disease specialist explained to El Confidencial.

Although it is not the long-awaited HIV vaccine that has been sought for years, Güerri believes that this treatment "is comparable to a vaccine in the sense that with two administrations per year, you are protected year-round."

The specialist summarizes that "ideally, if you had the entire at-risk population taking this treatment, HIV would disappear." This way, those already infected would continue receiving treatment for the virus, but there would be no new cases.

Challenges to implementing effective prevention

Despite progress, HIV prevention continues to face obstacles. In Spain, despite the availability of PrEP since 2019, the number of new HIV diagnoses remains high , with more than 3,000 cases annually, half of which are detected late. Furthermore, between 21% and 31% of PrEP users experience adherence problems, and one in four will discontinue treatment within the first year.

For Lenacapavir to have the expected impact on reducing new infections , it is crucial that health systems improve access to and adherence to preventive treatments. Without these changes, the opportunity to eradicate the HIV epidemic could be seriously compromised.

The challenge is clear: ensuring that those most in need can access preventive tools and maintain consistent treatment adherence . Only then can we make significant progress toward eliminating HIV globally.