HIV prevention drug found 100% effective in clinical trial

A large clinical trial in South Africa and Uganda has shown that a twice-yearly injection of a new pre-exposure prophylaxis drug gives young women total protection from HIV infection.

The trial tested whether the six-month injection of lenacapavir would provide better protection against HIV infection than two other drugs, both daily pills. All three medications are pre-exposure prophylaxis (or PrEP) drugs.

Physician-scientist Linda-Gail Bekker, principal investigator for the South African part of the study, tells Nadine Dreyer what makes this breakthrough so significant and what to expect next.

Related: We could end the AIDS epidemic in less than a decade. Here's how. 

Tell us about the trial and what it set out to achieve

The Purpose 1 trial with 5,000 participants took place at three sites in Uganda and 25 sites in South Africa to test the efficacy of lenacapavir and two other drugs.

Lenacapavir (Len LA) is a fusion capside inhibitor. It interferes with the HIV capsid, a protein shell that protects HIV's genetic material and enzymes needed for replication. It is administered just under the skin, once every six months.

The randomized controlled trial, sponsored by the drug developers Gilead Sciences, tested several things.