Pre-exposure Prophylaxis (PrEP) Adherence Enhancement Guided by iTAB and Drug Levels for Women

Inclusion Criteria: * Female at birth and identifies as female gender * Age 18 years or older * Able to understand and provide consent in English or Spanish * HIV negative by 4th generation test (Ag/Ab test) or combination of enzymeimmunoassay (EIA) and HIV RNA * Creatinine clearance ≥ 60 ml/min (via Cockcroft-Gault formula) At-Risk Criteria (at least one): * Condomless sex in the last 3 months with one or more male partners of unknown HIV status known to be at substantial risk of HIV infection (IDU, bisexual, sex for goods, recently incarcerated, from a country with HIV prevalence \>1%, interpersonal Partner Violence); * STI (rectal or vaginal gonorrhea or syphilis) diagnosis during the last 6 months. * Previous post-exposure prophylaxis (PEP) use during the last 12 months. * Has at least one HIV-infected sexual partner for ≥4 weeks. * Sex for exchange of money, goods or services Exclusion Criteria: * Pregnancy at enrollment. * Any condition, which in the opinion of the provider, will seriously compromise the participant's ability to comply with the protocol, including adherence to PrEP medication dosing, such as active, untreated or unstable major mental illness (i.e. untreated psychotic disorder). * Use of prohibited medications, in particular, agents known to be nephrotoxic or drugs slow in renal excretion. * Previous participation in an HIV vaccine trial. Participants that were documented to have received only placebo are not excluded. * Signs or symptoms suspicious for Primary HIV Infection (PHI).