Vaginal microbiome, antiretroviral concentrations, and HIV genital shedding in the setting of hormonal contraception initiation in Malawi.

Objective: The aim of this study was to understand how vaginal microbiota composition affects antiretroviral concentrations in the setting of hormonal contraception initiation.

Methods: Cervicovaginal fluid (CVF) concentrations of tenofovir, lamivudine, and efavirenz from 73 Malawian women with HIV were compared before and after initiation of depot-medroxyprogesterone acetate (DMPA) or levonorgestrel implant. We evaluated antiretroviral concentrations and vaginal microbiota composition/structure in the context of contraception initiation and predicted genital shedding using multivariable repeated measurements models fit by generalized estimating equations.

Results: Mean lamivudine CVF concentrations decreased 37% 1 month after contraception initiation. Subgroup analyses revealed a 41% decrease in women 1 month after initiating levonorgestrel implant, but no significant difference was observed in DMPA group alone. Tenofovir, lamivudine, and efavirenz CVF concentrations were positively correlated with anaerobic bacteria associated with nonoptimal vaginal microbiota. Risk of genital HIV shedding was not significantly associated with tenofovir or lamivudine CVF concentrations [tenofovir relative risk (RR): 0.098, P = 0.75; lamivudine RR: 0.142, P = 0.54]. Lack of association between genital HIV shedding and efavirenz CVF concentrations did not change when adjusting for vaginal microbiota composition and lamivudine/tenofovir CVF concentrations (RR: 1.33, P = 0.531).

Conclusion: No effect of hormone initiation on genital shedding provides confidence that women with HIV on either DMPA or levonorgestrel implant contraception will not have compromised ART efficacy. The unexpected positive correlation between antiretroviral CVF concentrations and certain bacterial taxa relative abundance requires further work to understand the mechanism and clinical relevance.