A once-a-year injection designed to protect against HIV has successfully passed an initial safety trial, according to research published in The Lancet medical journal.
The drug, lenacapavir, cleared a crucial Phase I trial and could become a highly effective and convenient option for HIV prevention.
How Lenacapavir Works
Lenacapavir prevents HIV from replicating inside cells, making it a potential alternative to existing PrEP (pre-exposure prophylaxis) options, which currently require either a daily pill or bi-monthly injections. These methods have already been shown to significantly reduce the risk of HIV transmission.
Early Trial Results Show Promise
The trial involved 40 HIV-negative participants receiving a muscle-directed injection of lenacapavir. No serious side effects or safety concerns were reported, and after 56 weeks, the drug remained detectable in their systems.
Researchers highlighted the potential impact of an annual PrEP injection:
“By decreasing dosing frequency and providing an additional PrEP option for people who want or need PrEP, yearly dosing of lenacapavir has the potential to further decrease current barriers to PrEP by increasing the uptake of, persistence on, and, therefore, scalability of PrEP,” they said.
Richard Angell, from the HIV charity Terrence Higgins Trust, expressed optimism about the findings in a statement to the BBC:
“PrEP as a daily pill has been a game-changer in our HIV response. The prospect of ‘safe’ annual injectable PrEP is as exciting as it is transformational. It’s great to see these early results that suggest injectable PrEP might be effective for up to 12 months.”
Challenges and Next Steps
While the results are promising, access to existing PrEP remains unequal. Angell pointed out that oral PrEP is still unavailable in prisons, online, and in community pharmacies. He emphasised the need for healthcare systems to prepare for the rollout of injectable PrEP and ensure proper funding for sexual health clinics.
With approximately 40 million people living with HIV—65% of whom are in Africa—researchers stressed the importance of ensuring that future trials include a diverse range of participants. Their findings were presented at the 2025 Conference on Retroviruses and Opportunistic Infections.
