Although approximately 50,000 Americans have filled at least one prescription for Truvada (tenofovir/emtricitabine) as pre-exposure prophylaxis, PrEP’s popularity is mostly limited to white men and those older than 25. Considering HIV’s disproportionate impact on young black men who have sex with men (MSM) in particular, these statistics suggest that PrEP’s overall impact on HIV infection trends, at least in the short term, may be compromised by such demographic factors.

Gilead Sciences, Truvada’s manufacturer, released its most comprehensive analysis of national PrEP use to date, presenting findings at the ASM Microbe 2016 conference in Boston.

Gilead based its analysis on data from 82 percent of all pharmacies that dispensed Truvada between January 1, 2012, and September 20, 2015. Previously, Gilead’s analyses on PrEP use were based on a smaller proportion of pharmacies, resulting in what were likely considerable underestimates of PrEP’s actual use. For this new analysis, Gilead adjusted its data to make projections on PrEP prescriptions filled at all retail pharmacies and “to a small extent, non-retail pharmacies.”

Because there is no specific prescription code for Truvada’s use as PrEP, Gilead relied on an algorithm that excluded prescriptions written for HIV or hepatitis B virus (HBV) treatment or post-exposure prophylaxis (PEP).

Quarterly rates of first-time PrEP users remained relatively constant through the third quarter of 2013, when 1,621 new prescriptions were filled. The rate then followed a steady upswing to 8,482 new prescriptions in the third quarter of 2015, a 523 percent increase. Considering that three subsequent quarters are unaccounted for in the analysis, the current figure for the total number of people who have at least tried PrEP could be considerably higher than 50,000 and still rising steadily.

Gilead conducted a demographic analysis of 21,463 people who have filled a PrEP prescription (43.7 percent of the total). Seventy-four percent of the users were white, 12 percent were Latino and 10 percent were African American. By comparison, a respective 27 percent, 24 percent and 44 percent of new HIV infections are among these racial groups.

Women constituted 20.7 percent of those filling new PrEP prescriptions across the period studied. The number of women filling a new prescription in each of the four years between 2012 and 2015 remained constant: between about 2,500 and 2,600. In the third quarter of 2015, 11.4 percent of new prescriptions were among women.

Just 7.6 percent of those who have been on PrEP were younger than 25 at the time of their first prescription.

Gilead researchers concluded that initiation of PrEP has been low among African Americans, Latinos, women and those younger than 25.

“HIV prevention education and PrEP services may need to be racially focused and culturally relevant to increase PrEP uptake and decrease new infections in populations at the greatest risk,” the Gilead report concluded.