Genital Herpes Simplex Virus Type 2 Suppression With Valacyclovir Is Not Associated With Changes in Nugent Score or Absolute Abundance of Key Vaginal Bacteria

BACKGROUND: In women, genital herpes simplex virus type 2 (HSV-2) infection is associated with increased risk for recurrent bacterial vaginosis (BV), but causal relationships are unclear. METHODS: Women with a self-reported history of BV and HSV-2 seropositivity self-collected vaginal and anogenital swabs for 2 nonconsecutive 28-day periods, in the absence or presence of valacyclovir suppressive therapy (500 mg daily). HSV polymerase chain reaction was performed on anogenital swabs; vaginal swabs were used for assessment of BV by Nugent score and quantification of vaginal microbiota. Days with BV, defined by Nugent score ≥7, were compared during the observational period and valacyclovir treatment. RESULTS: Forty-one women collected swabs for a median of 28 days (range, 20–32 days) each study period. The HSV-2 shedding rate decreased from 109 of 1126 days (9.7%) presuppression to 6 of 1125 days (0.05%) during valacyclovir (rate ratio [RR], 0.06 [95% confidence interval {CI}, .02–.13]). BV occurred on 343 of 1103 days (31.1%) during observation and 302 of 1091 days (27.7%) during valacyclovir (RR, 0.90 [95% CI, .68–1.20]). The median per-person Nugent score was 3.8 during observation and 4.0 during valacyclovir. Average log(10) concentrations of vaginal bacterial species did not change significantly during valacyclovir treatment. CONCLUSIONS: Short-term HSV-2 suppression with valacyclovir did not significantly affect the Nugent score or the vaginal microbiome despite potent suppression of HSV-2 shedding.