After two decades of stagnation, the Centers for Disease Control and Prevention’s (CDC) estimate of the annual number of new HIV infections in the United States
fell 18 percent between 2008 and 2014, from 45,700 to 37,600 per year.

During this time, the estimated infection rate, or incidence, declined 56 percent among injection drug users (IDUs), to 1,700 new cases, and 36 percent among heterosexuals, to 8,600 cases. Men who have sex with men (MSM), on the other hand, saw only a leveling off of new annual transmissions, at about 26,000 per year—which nonetheless is a sign of significant progress for a group that had previously seen rising rates and accounts for 70 percent of all new infections.

Among MSM, rates held steady for Blacks at about 10,000 per year during the six-year period; dropped 18 percent among whites, to 7,400 cases; and rose 20 percent among Latinos, to 7,300 cases. For 13- to 24-year-old MSM, the rate dropped 18 percent, to 7,700 cases, and for 25- to 34-year-old MSM, the rate increased 35 percent, to 9,700 cases.

“The declines in national incidence, likely driven by [HIV] treatment as prevention, are exciting,” says Demetre Daskalakis, MD, MPH, acting deputy commissioner for the Division of Disease Control at the New York City Department of Health and Mental Hygiene. Referring to Truvada (tenofovir disoproxil fumarate/emtricitabine) as pre-exposure prophylaxis (PrEP), he said, “As PrEP uptake increases, incidence declines should be further accelerated.”

The CDC arrived at its estimates by analyzing and applying statistical models to HIV diagnosis data as well as post-diagnosis CD4 counts reported to the National HIV Surveillance System.