Inclusion Criteria:  age 18 years or older (confirmed by ID) self-identify as either a cisgender or transgender woman eligible for and willing to initiate PrEP or already on PrEP [having initiated PrEP within the last three months per participant self-report] documented negative HIV test result at Screening Visit Has a mobile phone with a minimum of 3G network with an active cellular plan no signs/symptoms of acute HIV infection normal renal function (eCrCl of >/= 60 ml/min) not taking contraindicated medications documented negative hepatitis B virus (HBVAg) status or documented evidence of seroimmunity if HCV Ab positive, documented evidence of previous completed treatment, resolution of active HCV infection (i.e. documented negative HCV RNA), or documented evidence of PCP/HCV care provider management/treatment progress meets CDC criteria for HIV risk willing to complete all required study procedures including the use of Truvada.  Exclusion Criteria:  age under 18 years; HIV-positive status based on documented test results at at Screening or Enrollment Visits; any sign or symptom of acute HIV infection at screening or enrollment visit, until HIV status is confirmed negative via HIV RNA PCR testing; renal function, eCrCl< 60 mL/min at Screening or Enrollment visit; inability to provide informed consent; pregnancy or breast-feeding; plans to move away from NYC area in the next 12-month period; Current use of HIV post-exposure prophylaxis (PEP), though participants who wish to transition from PEP to PrEP will be eligible at the completion of PEP Continued need for/use of medications with potential for adverse interactions with Truvada (FTC/TDF) or Descovy (TAF/FTC) on a case-by-case basis, i.e., hepatitis C antiviral agents, such as EPCLUSA (sofosbuvir/velpatasvir) or VOSEVI (sofosbuvir/velpatasvir/voxilaprevir); NRTIs, such as didanosine; medications that may decrease renal function (i.e., high-dose or multiple NSAIDS, aminoglycosides; and other medications that may result in compromising a participant's overall health if combined with Truvada, per the discretion of the IOR; History of self-reported low adherence to PrEP, based on study team's judgement