When HIV pre-exposure prophylaxis (PrEP) pills were first approved by the Food and Drug Administration in 2012, some states took a wait-and-see approach to offering it to their residents. They would watch the early adopters—states like Massachusetts, New York and Connecticut—and see how it panned out.

Now, according to data published in Open Forum Infectious Diseases, that decision has put its residents who could benefit from PrEP at risk.

Samuel Powers, a research associate working with Kate McManus, MD, at the University of Virginia Division of Infectious Diseases, and colleagues took data on the number of people using PrEP by state from AIDSVu.org and looked at estimates from the Centers for Disease Control and Prevention (CDC) on the number of people in the same states who could benefit from PrEP. They did this for 2014 and 2016 to 2018.

The lowest-uptake states in 2014 started an average of 3% behind early adopters. And PrEP use seemed to build on itself: For every 5% of PrEP use in 2016, for instance, PrEP use rose by 1.18% in 2017 and so on, meaning that the states that didn’t start rolling out PrEP until later years started out at a disadvantage, and that disadvantage grew every year as they tried to catch up.

The states most behind in offering PrEP? According to the study, they were Wyoming, Idaho, Indiana, Alaska and Montana.

By 2018, those states hadn’t changed much, with increases in PrEP use lagging significantly behind those of states with high increases in PrEP use. For instance, PrEP use rose the most in the Northeast between 2014 and 2018 (by 17%), rose the least in the South and the West (both by 7%) and increased by 9% in the Midwest during the same period. For instance, by 2018, PrEP use in New York, the number 1 state on the list, had increased by nearly 30%. But in Wyoming, the rate edged higher by just 2.35%.

This is not what Powers and colleagues were hoping to see.

“We would expect a negative trend, with late adoption predicting larger gains, as low-uptake states catch up to early adopters,” they wrote. “Yet, in 2014 to 2015, we see greater prior PrEP use predicting increased growth. This results in increasing disparities in PrEP access between early- and late-adopting states, suggesting that underperforming states are not ‘catching up.’”

Click here to read the full study.

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