King County public health HIV control efforts include tracking viremia and drug resistance, and promotion of antiretroviral adherence and reduction of viremia among people living with HIV (PLWH). A possible transmission of a tenofovir (TDF)/emtricitabine (FTC) resistant virus to a PLWH reporting good adherence to pre-exposure prophylaxis (PrEP, comprised of TDF and FTC) in 2016 initiated interventions with viremic PLWH with TDF/FTC resistant virus to help prevent transmission of an HIV strain potentially rendering PrEP ineffective.
HIV genotypic and viral load (VL) data from King County HIV surveillance were used to identify viremic PLWH with TDF/FTC resistant HIV. Resistance was defined by the Stanford database algorithm and based on any reported genotypic test. Resistance to TDF/FTC was defined by intermediate to high level resistance to both components. Viremia was defined as a most recent (within 2 years) plasma VL 1,000+ copies per mL. The Care and Antiretroviral Promotion Project (CAPP) investigated two prior viremic TDF/FTC resistant cohorts, working with individuals who are poorly engaged in HIV care to overcome barriers to care and antiretroviral adherence.
Of 6,798 King County PLWH, genotypic sequences were reported for 3,892 (57%). Intermediate to high level TDF/FTC resistance was found for 251 (6%). We identified 368 PLWH (6% excluding 422 with no VL in 2 years) with viremia, and 8 had TDF/FTC resistance. Including 17 PLWH with no reported VL testing in two years and TDF/FTC resistance, 25 PLWH had TDF/FTC resistance and either viremia or no recent VL (corresponding to 0.4% of PLWH). Assuming the 43% of individuals with no reported genotype had similar levels of resistance we estimate that an additional 17 PLWH (42 total) may have no VL or viremia and TDF/FTC resistance, corresponding to 0.6% of PLWH. Investigation outcomes are summarized in the figure, and include (1) that nearly half of individuals without a VL were from a facility not reporting VL, all were virally suppressed or relocated and (2) at least 7 had previously completed the CAPP intervention and remained viremic or without VL, including 2 referred to a clinic providing extensive support to PLWH unable to achieve viral suppression.
FTC/TDF drug resistance among viremic PLWH in King County, WA remains rare, estimated in 0.4-0.6% of PLWH. We have developed outreach programs for these persons, designed to promote care and prevent transmission of HIV with TDF/FTC resistance.