SEATTLE – Bacterial vaginosis does not decrease the effectiveness of oral pre-exposure prophylaxis (PrEP) for HIV prevention, according to an investigation of 1,470 women in Africa.
Daily oral PrEP with tenofovir pills was 77% effective in protecting women with bacterial vaginosis from HIV, and 73% effective in women who did not have BV over the 3-year study. The difference was not statistically significant.Renee Heffron, PhD, of the department of global health at the University of Washington, Seattle, and her colleagues concluded in a presentation of their findings at the Conference on Retroviruses & Opportunistic Infections in partnership with the International Antiviral Society.
Bacterial vaginosis in PrEP has been a concern ever since it was reported in the summer of 2016 that vaginal tenofovir gel didn’t prevent HIV in women with the condition. “Our results provide reassurance ... We [saw] no evidence that oral PrEP effectiveness was reduced in East African women with Gram stain evidence of BV or vaginal dysbiosis. Oral PrEP delivery to women does not need to be accompanied by testing for BV,” Dr. Heffron said.
It’s likely that Gardnerella vaginalis degrades topical tenofovir when applied vaginally; oral administration bypasses the effect.
The findings come from a subanalysis of the Partners PrEP Study, a phase III trial of daily oral PrEP in Kenya and Uganda. The investigators broke out PrEP results according to BV status, with BV defined as a Nugent score of 7-10, assessed annually. Adherence was high in the 985 women randomized to PrEP, at about 80%.
There were 0.9 cases of newly acquired HIV per 100 person-years among women in the BV PrEP group, versus 3.5 per 100 person-years among BV women not on prep. PrEP was about 63% effective in women with intermediate Nugent scores of 4-6. The differences in HIV protection according to Nugent score were not statistically significant (P = .9).
It didn’t matter if women had Gardnerella, Bacteroides, or Lactobacillus morphotypes. All three are markers of abnormal vaginal microbiota, but PrEP still worked.
The median age in the study was 33 years, and 24% of the women had BV at baseline.
Dr. Heffron did not report any disclosures. The Gates Foundation and other sources funded the work.