Using GPS data to deliver HIV interventions to people who need them most

Black sexually minoritized men and transgender women face disproportionately high HIV rates in the U.S., with 50% of Black sexually minoritized men predicted to contract HIV by the age of 49.

Unfortunately, these groups also face significant barriers to accessing HIV prevention and treatment, such as geographic disparities, limited neighborhood resources, and HIV-related stigma and discrimination.

A recent study led by researchers at the University of Chicago Medicine used GPS data to identify venues in the Chicago area where public health experts can most effectively reach Black sexually minoritized men and transgender women with HIV interventions.

“It’s important to note that Black sexually minoritized men and transgender women are at the highest risk for acquiring HIV not because they have more sex, use more drugs or are ‘more risky’ in stereotypical ways,” said senior author John Schneider, MD, MPH, an epidemiologist and infectious disease specialist at UChicago Medicine. “It comes down to a lot of the factors that impact the health of these communities in general, such as over-policing, housing instability, under- and unemployment — all the social and structural factors that drive poor health. And within sexual and gender minorities, it's a smaller network of people, so if HIV gets into that network, it's more likely to spread.”

Public health experts can’t simply pick high-risk individuals out of a crowd, so they strategically aim to engage people in social spaces like cafés, bars or even parking lots that are common meeting areas for certain communities. At those venues, they can provide resources like educational materials, condoms and on-site HIV testing, along with referrals to clinics that offer pre-exposure prophylaxis (PrEP), a medication that can prevent HIV infection, and antiretroviral therapy (ART).

As part of participating in the Neighborhood and Networks (N2) Study, which Schneider also leads, Black sexually minoritized men and transgender women in the Chicago area carried small GPS devices around with them for several weeks, pinging their location to researchers every five seconds. Unlike previous studies that relied heavily on self-reporting, Schneider and his fellow researchers could be certain of the frequency with which people visited each location, the amount of time spent, and the order in which an individual visited multiple locations.

“Using GPS, we can track the specific social spaces people visit and identify distinct patterns, almost like a behavioral fingerprint. For example, one person might frequent a bar, a park and a clinic, while another might visit a café, a cruising area and a pharmacy. This unique combination of behavior and environment is what drives HIV risk,” Schneider said. “By analyzing these patterns and integrating data from surveys and blood samples, we can identify subgroups — such as younger individuals or those who experience unstable housing — with different risks of acquiring HIV or differing abilities to access prevention and treatment.”

Schneider says in the absence of these insights, healthcare and public health professionals resort to putting HIV prevention and education materials in well-known, high-throughput locations, but there’s no guarantee that the groups frequenting those locations include the people most in need of HIV interventions.

In contrast, Schneider and his colleagues were able to pinpoint two key Chicago entertainment venues that are particularly influential among people who don’t yet use PrEP and those who reported a higher number of casual sex partners. By targeting just those two venues, public health efforts could reach over half of the participants not taking PrEP, compared to just 30% who would be reached by targeting only the most well-known, high-throughput location within the vulnerable community.

“This targeted approach represents a refinement of traditional public health models,” Schneider said. “We only have so many health resources, so it makes a difference if we can focus those resources on the communities most impacted by health problems for which we have interventions.”