Findings Give Hope for Monthly HIV Prevention Pill

From the IAS Conference in Kigali (image source)

By Anna Miti in Kigali, Rwanda A new monthly HIV prevention pill that could offer up to a month of protection per dose has taken a major step forward after receiving approval to proceed to pivotal phase three trials. The experimental drug, currently named MK-8527, was the focus of high-level discussion at the International AIDS Society (IAS) conference held in Kigali, Rwanda this week.

Early research shows promise. Data from the phase two clinical study, conducted in South Africa, the United States, and Israel, indicated that the pill was well tolerated, showed a favorable safety profile, and maintained required antiretroviral levels in participants’ bodies. Although the trial was not intended to confirm efficacy, no participant acquired HIV during the study period. The phase two study involved 350 participants, around one-third of whom were from South Africa. They were assigned different doses — 3mg, 6mg, or 12mg — or a placebo, and took one pill per month for six months. Participants were then monitored for at least two more months. The encouraging results pave the way for phase three studies, where researchers will determine whether the monthly pill is clinically effective in preventing HIV infection.

The upcoming phase three trials will be conducted across multiple countries and will compare MK-8527’s efficacy with existing daily oral HIV prevention pills currently offered in the Zimbabwean public health system. These daily pills typically contain the antiretroviral drugs tenofovir disaproxil fumarate and emtricitabine, which have already proven highly effective in curbing HIV transmission.

If successful, MK-8527 would join a growing arsenal of HIV prevention tools. These include a daily oral pill, two types of injectable antiretroviral shots offering 2- and 6-month protection, and a monthly vaginal ring designed for women. Each of these options plays a role in providing patients with flexible, accessible prevention choices—especially in resource-constrained environments. The drug’s developer, Merck, appears optimistic about the pill’s future and is pushing forward on an “aggressive timeline” to make MK-8527 widely available if final trials prove successful.

“We are pursuing very optimistic and aggressive timelines,” said Dr Rebecca Plank, a clinical research scientist at Merck, during a press briefing at the IAS conference.

Final results from the phase three studies are expected in two or more years, but health advocates, scientists, and public health officials are already watching closely. A monthly oral HIV prevention pill could significantly improve adherence rates, offer greater convenience, and help reduce new HIV infections—particularly in sub-Saharan Africa where the burden remains high.