Public health agencies across the United States have spent years directing overdose prevention resources, HIV testing, and hepatitis C treatment toward people who inject drugs. But they've been working without a reliable answer to the most basic question: how many of those people are actually out there?
The last standardized, city-level count of people who inject drugs in the U.S. dates to 2007, before fentanyl dominated the drug supply, before injection-related HIV outbreaks erupted in Indiana, West Virginia, and Massachusetts, and before the demographics of drug use shifted dramatically toward younger, more urban populations. Without current numbers, cities cannot calculate accurate rates of overdose or infection, cannot measure whether their interventions are working, and struggle to make the case for more funding.
Researchers at Emory University in Atlanta are now moving to close that gap. The team received a $748,287 federal grant from the National Institute on Drug Abuse to produce updated population estimates for people who inject drugs in 11 large U.S. cities, broken down by age. They'll work directly with each city's health department, using a combination of overdose death records, HIV and hepatitis C diagnosis rates, and spatial modeling to map where injection drug use is concentrated and where services are or aren't reaching people.
The stakes are high. The federal government has directed tens of billions of dollars toward the opioid crisis since declaring it a public health emergency in 2017, including major funding streams under the SUPPORT Act and CDC's Ending the HIV Epidemic initiative. All of that resource allocation depends on knowing the size of the at-risk population in a given place. Without it, targeting is largely guesswork.
Age breakdown matters especially because overdose risk and infectious disease exposure vary significantly across age groups, and the most effective interventions differ accordingly. A city where injection drug use is concentrated among people in their 20s needs different services than one where it's prevalent among people over 40.
Emory is a natural home for this work. The university's Rollins School of Public Health houses AIDSVu and HepVu, widely used platforms that map HIV and hepatitis C data at local levels. Findings from the new project will be published through both platforms, and the team plans to build a public resource center so other cities not included in the initial 11 can run their own estimates using the same methods. Similar geo-targeting approaches are already being used in other states: Connecticut has used spatial data to direct a mobile pharmacy to drug users most at risk for HIV.
The 11 cities involved haven't been named publicly. Results are expected to become available through the AIDSVu and HepVu platforms as the research progresses.
