Background: Daily oral preexposure prophylaxis (PrEP) using the antiretroviral tenofovir disoproxil fumarate (TDF) alone or in combination with emtricitabine (FTC–TDF) reduces the risk for HIV-1 acquisition. Tenofovir has in vitro activity against herpes simplex virus type 2 (HSV-2).
Objective: To assess the efficacy of daily oral PrEP with tenofovir and FTC–TDF in the prevention of HSV-2 acquisition.
Design: Subgroup analysis of data from a randomized, placebo-controlled trial with concealed allocation. (ClinicalTrials.gov: NCT00557245)
Setting: Multiple sites in Kenya and Uganda.
Participants: Heterosexual men and women who were seronegative for HIV-1 and HSV-2 and at high risk for HIV-1 acquisition due to having an HIV-1–infected partner.
Measurements: HSV-2 seroconversion.
Results: A total of 131 participants seroconverted to HSV-2 (79 of 1041 assigned to tenofovir or FTC–TDF PrEP [HSV-2 incidence, 5.6 per 100 person-years] and 52 of 481 assigned to placebo [HSV-2 incidence, 7.7 per 100 person-years]). The hazard ratio (HR) for HSV-2 acquisition with daily oral PrEP was 0.70 (95% CI, 0.49 to 0.99; P = 0.047) compared with placebo, and the absolute risk reduction was 2.1 per 100 person-years. Among the 1044 participants with HSV-2–infected partners, the HR for PrEP was 0.67 (CI, 0.46 to 0.98; P = 0.038) compared with placebo, and the absolute risk reduction was 3.1 per 100 person-years.
Limitation: Randomization was not stratified by HSV-2 status, and diagnostic tests to exclude participants with acute HSV-2 at baseline are not available.
Conclusion: Daily oral tenofovir-based PrEP significantly reduced the risk for HSV-2 acquisition among heterosexual men and women. Modest protection against HSV-2 is an added benefit of HIV-1 prevention with oral tenofovir-based PrEP.
Primary Funding Source: Bill & Melinda Gates Foundation.