A single yearly injection designed to prevent HIV infection has cleared its first major safety hurdle, raising hopes for a new form of long-acting protection against a virus that still affects nearly 40 million people worldwide. Researchers published results in The Lancet showing that lenacapavir — a drug that works by stopping HIV from replicating inside cells — remained detectable in participants’ bodies for 56 weeks after a single shot, with no major side effects.
At a glance
- Lenacapavir trial: Forty HIV-negative participants received a single intramuscular injection; after 56 weeks, the drug was still present in their systems with no serious safety concerns recorded.
- Annual HIV prevention: If future trials succeed, this would become the longest-acting form of pre-exposure prophylaxis (PrEP) available — a significant step beyond current daily pills or eight-weekly injections.
- HIV epidemic scale: Approximately 39.9 million people live with HIV globally, with 65% of cases concentrated in the WHO African Region as of 2023 C.E., making scalable prevention tools especially urgent.
Why this matters for HIV prevention
PrEP — pre-exposure prophylaxis — already works well. Daily oral pills reduce the risk of acquiring HIV by more than 99% when taken consistently. But that word, “consistently,” is where the challenge lies.
Remembering a pill every single day is difficult for anyone. For people navigating unstable housing, stigma, busy caregiving schedules, or limited access to pharmacies, the daily pill model creates real gaps in protection. A once-yearly injection could sidestep many of those barriers in a single visit.
Researchers presented the findings at the 2025 C.E. Conference on Retroviruses and Opportunistic Infections. They noted that “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.” In plain terms: more people could stay protected for longer, with less friction.
Building on earlier lenacapavir results
Lenacapavir is not new to the HIV field. It already holds approval as a treatment for drug-resistant HIV infections, administered twice a year. Earlier in 2024 C.E., two large trials — PURPOSE 1 and PURPOSE 2 — found that twice-yearly lenacapavir injections for PrEP showed striking efficacy results, generating significant attention from global health organizations.
This new Phase I trial is specifically testing a once-yearly dosing schedule, which would halve the number of injections required. Phase I trials focus primarily on safety and tolerability rather than efficacy, so the results don’t yet confirm whether an annual dose prevents infection — that question awaits larger, later-stage trials. Still, passing this hurdle cleanly is a necessary and meaningful step.
Gilead Sciences, the manufacturer of lenacapavir, has been under pressure from global health advocates to ensure affordable access to the drug in lower-income countries, where the burden of new HIV infections is highest. Negotiations around licensing and pricing will shape whether this innovation reaches the people who need it most.
Access gaps that still need closing
Even existing PrEP options face stubborn distribution problems. In the U.K., for example, the oral pill remains unavailable in prisons, online, or through community pharmacies. Scotland’s Medicines Consortium approved two-monthly PrEP injections in 2025 C.E., but England is still awaiting a green light from NICE — the National Institute for Health and Care Excellence.
Richard Angell of the Terrence Higgins Trust, a U.K.-based HIV charity, welcomed the early results while pointing to the preparedness work still needed. “We need to get ready for its rollout now and fund sexual-health clinics to do so,” he said. Researchers also acknowledged that future trials must include more diverse participants to ensure findings hold across different populations — an important gap to address before any approval process begins.
The World Health Organization, UNAIDS, and the Global Fund are all pursuing strategies to end the HIV epidemic by 2030 C.E. A once-yearly prevention injection, if proven effective and made widely accessible, would be a powerful addition to that toolkit. It won’t be the whole answer. But it could meaningfully change what protection looks like for millions of people — especially those for whom daily medication has never been a realistic option.
The road from a 40-person safety study to a licensed annual injection is long, and significant trials remain ahead. But the first step has been taken, and it went well.
Read more
For more on this story, see: BBC News
For more from Good News for Humankind, see:
- Alzheimer’s risk cut in half by drug in landmark prevention trial
- Renewables now make up at least 49% of global power capacity
- The Good News for Humankind archive on global health
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