Adherence, Preference, and Acceptability of an Overencapsulated Dual Prevention Pill for HIV and Pregnancy Prevention Among Women in Johannesburg, South Africa

INTRODUCTION: Oral preexposure prophylaxis (PrEP) is safe and effective for HIV prevention, but use among women has been suboptimal. A dual prevention pill (DPP) coformulating PrEP and a combined oral contraceptive (COC) may increase PrEP use. METHODS: We conducted a crossover study comparing an overencapsulated PrEP and COCs capsule (DPP) with PrEP and COCs taken separately (2-pill regimen [2 PR]) among in Johannesburg, South Africa. We randomized (1:1) 18- to 40-year-old female participants to regimen sequence: DPP followed by 2 PR for ∼3 months each, or the reverse, plus an optional choice period (≤6 m). Primary outcomes were stated regimen "preference" after the crossover period (exact binomial test; proportion = 0.5) and "adherence" defined as tenofovir diphosphate (TFV-DP) levels in monthly dried blood spots (DBS) indicating ≥4 PrEP doses/week (mixed-effects logistic regression). Safety and acceptability were secondary outcomes. RESULTS: Of 96 participants (mean age, 27.4 years) enrolled, 85 completed the crossover period (August 2022-January 2024), 62% of whom preferred the 2 PR vs 38% the DPP capsule (P = 0.037). Few participants (7%) were always adherent (per DBS samples) and 0.05). Most adverse events were mild/moderate and similar between the regimens. More than 80% found both regimens easy to use, although >75% reported challenges swallowing the DPP and/or PrEP tablet. CONCLUSIONS: Although more participants preferred the 2 PR, a substantial minority preferred the DPP, highlighting the importance of choice. Adherence to both regimens was low. Studies with the smaller coformulated tablet will be important for assessing the DPP's ultimate impact on HIV prevention. CLINICAL TRIAL NUMBER: NCT04778527.