Preexposure Chemoprophylaxis for HIV Prevention

To the Editor: Grant et al. (Dec. 30 issue) 1 report that once-daily emtricitabine−tenofovir (FTC−TDF) provided 44% relative risk reduction from human immunodeficiency virus (HIV) infection in a high-risk population. In their discussion and in the accompanying editorial, 2 potential limitations of this approach to curb the HIV epidemic, including side effects (e.g., renal insufficiency), the potential emergence of drug resistance (in patients with HIV and hepatitis B virus infection), and medication-use fatigue, are detailed. The economic implications of this prevention method, however, are not discussed. Given the absolute risk reduction of 2.26 percentage points reported in the study, about 44 people . . .