HIV Incidence, HIV Prevalence, and Undiagnosed HIV Infections in Men Who Have Sex With Men, United States.

Background: HIV infection is a persistent health concern in the United States, and men who have sex with men (MSM) continue to be the most affected population. Objective: To estimate HIV incidence and prevalence and the percentage of undiagnosed HIV infections overall and among MSM. Design: Cross-sectional analysis. Setting: National HIV Surveillance System. Participants: Persons aged 13 years or older with diagnosed HIV infection. Measurements: Data on HIV diagnoses and the first CD4 test result after diagnosis were used to model HIV incidence and prevalence and the percentage of undiagnosed HIV infections from 2008 to 2015 on the basis of a well-characterized CD4 depletion model. Results: Modeled HIV incidence decreased 14.8% overall, from 45 200 infections in 2008 to 38 500 in 2015, and among all transmission risk groups except MSM. The incidence of HIV increased 3.1% (95% CI, 1.6% to 4.5%) per year among Hispanic/Latino MSM (6300 infections in 2008, 7900 in 2015), decreased 2.7% (CI, -3.8% to -1.5%) per year among white MSM (8800 infections in 2008, 7100 in 2015), and remained stable among black MSM at about 10 000 infections. The incidence decreased by 3.0% (CI, -4.2% to -1.8%) per year among MSM aged 13 to 24 years and by 4.7% (CI, -6.2% to -3.1%) per year among those aged 35 to 44 years. Among MSM aged 25 to 34 years, HIV incidence increased 5.7% (CI, 4.4% to 7.0%) per year and among MSM aged 55 years and older, HIV increased 4.1% (CI, 0.8% to 7.4%). The percentage of undiagnosed HIV infections was higher among black, Hispanic/Latino, and younger MSM than white and older MSM, respectively. Limitation: Assumptions of the CD4 depletion model and variability of CD4 values. Conclusion: Expansion of HIV screening to reduce undiagnosed infections and increased access to care and treatment to achieve viral suppression are critical to reduce HIV transmission. Access to prevention methods, such as condoms and preexposure prophylaxis, also is needed, particularly among MSM of color and young MSM.