People living with diagnosed HIV who have a strain of the virus that is resistant to both of the meds included in Truvada (tenofovir disoproxil fumarate/emtricitabine) and also have a viral load high enough to be significantly transmissible are rarities. This finding, from an analysis of the HIV population in King County, Washington, which includes Seattle, is reassuring in the face of worries about how commonly people who stick to the daily Truvada as pre-exposure prophylaxis (PrEP) regimen might contract drug-resistant virus. Researchers estimate that about 35 people living with diagnosed HIV in King County, or 0.9 percent of the local HIV population, have a viral load above 1,000 and at least some resistance to the drugs in PrEP. Since 2008, only 0.17 percent of county residents who received resistance testing at the time of their HIV diagnosis have contracted a viral strain resistant to both drugs in Truvada.