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Vaginal TFV gel may protect against HSV-2 in women

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February 23, 2019

Photo of Jeanne Marrazzo
Jeanne M. Marrazzo

After controlling for sexual behavior and HIV-1 acquisition, adherence to vaginal tenofovir gel was associated with a trend toward reduced risk for herpes simplex virus type-2 in women, according to a secondary analysis of the Vaginal and Oral Interventions to Control the Epidemic, or VOICE, trial.

VOICE was a randomized, double-blind, placebo-controlled trial that assessed the daily use of oral and vaginal tenofovir (TFV) for HIV-1 pre-exposure prophylaxis (PrEP). Researchers previously reported that findings from the trial showed low PrEP adherence and low or even no protection against HIV, likely due to low adherence. A reanalysis of the trial published in 2015 suggested that despite the low adherence, the gel was effective for PrEP and guarded against infection among the women who used it.

Writing in The Journal of Infectious Diseases, Jeanne M. Marrazzo, MD, MPH, Infectious Disease News Editorial Board member and director of the division of infectious diseases at the University of Alabama at Birmingham School of Medicine, and colleagues explained that a separate trial conducted among women in South Africa demonstrated a 51% reduction in the risk for HSV-2 in women who used TFV gel.

Similarly, the secondary analysis of the VOICE trial assessed the association between TFV gel adherence and HSV-2 acquisition risk. Marrazzo and colleagues measured the estimated effect of vaginal TFV 1% gel for preventing HSV-2 acquisition among women aged 18 to 45 years enrolled in the trial. At the first quarterly visit, TFV was measured in plasma to assess gel use, according to the study.

A total of 566 women were eligible for the secondary analysis. Marrazzo and colleagues identified 92 incident HSV-2 cases over a follow-up period of 501 person-years. Of those, 77 cases were in women who had no detected TFV plasma compared with 15 cases among women who were adherent to TFV gel. Adherence to TFV gel and subsequent detection of TFV plasma was associated with a trend toward reduced risk for HSV-2 seroconversion (unadjusted HR = 0.59). After adjusting for study site, age, two or more sex partners, hormonal contraception, anal sex and HIV status, the HR was 0.6.

“[The results] demonstrate that biomedical interventions — namely, provision of a drug with anti-herpes activity—can actually prevent HSV-2 acquisition through sex. This is important because we still don’t have a realistic candidate for a vaccine against HSV-2 in our near future, and because it is such a potent amplifier of HIV acquisition risk,” Marrazzo told Infectious Disease News.

“About one in five to one in six young women in the U.S. get new infections with HSV-2 annually, and in Africa, it is even higher and increases risk of HIV acquisition,” Marrazzo said. “I think there is a lot of potential as well for combining it with hormonal contraception in a vaginal ring or other device, as is being studied now.” – by Marley Ghizzone

Disclosures: The authors report no relevant financial disclosures.

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