New Delhi | An HIV-preventive drug showed 100 per cent efficacy and "no safety concerns" in women, according to a study published in The New England Journal of Medicine.

Lenacapavir, injectable twice a year, is developed by the US-based biopharmaceutical company Gilead Sciences, Inc. as a pre-exposure prophylaxis (PrEP) drug. These drugs prevent the spread of infection in people not yet exposed to the disease-causing agent.

The study, a phase-3 trial involving teenage girls and young women in South Africa and Uganda, showed that lenacapavir "demonstrated zero (HIV) infections" and "100 per cent efficacy," Gilead Sciences, Inc. said in a statement.

HIV, or human immunodeficiency virus, spreads from the body fluids of an infected person. Untreated, the infection can progress to AIDS or acquired immunodeficiency syndrome over years.

In the PURPOSE 1 trial, 5,338 participants, who were HIV-negative, to begin with, were divided into three groups - 2,134 receiving lenacapavir injections 26 weeks apart; 2,136 receiving the daily oral tablet Descovy (F/TAF); and 1,068 receiving the daily oral tablet Truvada (F/TDF).

Researchers, including those from the Desmond Tutu HIV Centre, University of Cape Town, South Africa, observed a total of 55 infections - zero in the Lenacapavir group, 39 in the Desovy group and 16 in the Truvada group.

"No participants receiving twice-yearly lenacapavir acquired HIV infection," the study authors wrote.

The most common adverse effects were injection-site reactions experienced by close to 70 per cent of the participants in the Lenacapavir group. However, there were "no serious injection-site reactions," according to the statement.

"These stellar results show that twice-yearly lenacapavir for PrEP, if approved, could offer a highly effective, tolerable and discreet choice that could potentially improve PrEP uptake and persistence, helping us to reduce HIV in cisgender women globally," first author Linda-Gail Bekker, Director of the Desmond Tutu HIV Center at the University of Cape Town, South Africa, said in the statement.

Results of PURPOSE 2 trial, involving cisgender men, transgender men, transgender women and gender non-binary individuals in countries, including Latin American ones, South Africa and Thailand, are expected in late 2024 or early 2025, the statement said.