Long-Acting PrEP Solutions for At-Risk Populations

A new study from Brown researchers examines more effective medication adherence strategies for PrEP among men who have sex with men in the U.S.

For HIV prevention, a daily pill known as pre-exposure prophylaxis, or PrEP, is a lifeline for high-risk populations. However, staying faithful to this daily regimen isn’t always straightforward, and lapses can compromise its effectiveness.

There are many reasons people don't stick with PrEP, including cost, disruption to daily routines, HIV-related stigma, and fear of real and perceived side effects of the medication. 

Recognizing this challenge, researchers from Brown University, Washington University School of Medicine, and University of Mississippi Medical Center recently conducted a study, published in BMC Public Health, examining the barriers to PrEP adherence. The study found that novel long-acting PrEP medications, such as injections, implants and monthly pills, have the potential to aid high-risk populations in adhering to PrEP regimens. Researchers believe it is necessary, however, that insurance companies cover these long-acting medications and health care providers inform patients of their safety and efficacy. 

To conduct the study, researchers held interviews with a racially representative group of 49 men who have sex with men (MSM) at clinics in Providence, Rhode Island; St. Louis, Missouri; and Jackson, Mississippi. Their goal was to gather information on patients’ beliefs about how the medication is delivered to help develop strategies for implementing long-acting PrEP for this population in real-world settings.

In the United States, HIV disproportionately affects gay, bisexual and other MSM—these populations accounted for 68% of new HIV cases in 2020. There are also significant disparities among racial and ethnic groups: Black MSM face a 1 in 2 lifetime risk of contracting HIV, compared to a 1 in 11 risk for White MSM, and 1 in 5 risk rate for Hispanic/Latino MSM.

“We conducted this study because many of our patients struggle with adherence to daily medications, or experience prohibitively high copayments at the pharmacy. We wanted to understand their thoughts about how we could enhance their experience with PrEP.”

Amy Nunn Professor of medicine and of behavioral and social sciences, executive director of Open Door Health
Woman smiling

One Brown University-led study from 2019 found that only 72% of MSM at three clinics across the U.S. were still on PrEP after three months, dropping to 57% after six months. Contemporaneous studies showed that, in San Francisco, 38% of users stopped PrEP within 13 months, and in the Bronx health system, retention at six months was only 42%.

“We conducted this study because many of our patients struggle with adherence to daily medications, or experience prohibitively high copayments at the pharmacy,” said Amy Nunn, co-principal investigator of the study and professor of medicine and of behavioral and social sciences at Brown. “We wanted to understand their thoughts about how we could enhance their experience with PrEP. Importantly, we wanted this research to inform and improve public policy on this issue.”

Nunn and her team - including Dr. Philip Chan, co-principal investigator of the study and associate professor of behavioral and social sciences and medicine at Brown -  introduced patients to three promising new PrEP delivery systems: injections, subdermal implants, and a monthly pill.

Subdermal implants can provide protection against HIV for up to one year, and long-lasting pill formulations last for a month. Recent clinical trials have shown that injectables, given once every eight weeks, are just as effective as daily oral pills in preventing HIV. One such injectable, intramuscular cabotegravir (IM-CAB), was approved by the FDA in December 2021 because it demonstrated superior efficacy compared to the daily pill. Despite FDA approval, IM-CAB is not yet included in most formularies, limiting its availability through drug plans or insurance.

“Injectable prep is administered every other month and is a great option for patients who may have trouble with adherence, who prefer not to take any medications, or who want to use a discrete form of PrEP,” said Nunn. “This is why we are very focused on this issue.”  

However, costs cast a shadow over the long-acting options. The price of injections, at approximately $3,000, significantly eclipses that of generic daily pills, which average around $1 a day. Expanding accessibility hinges on insurance companies providing coverage, especially for individuals dependent on government programs like Medicaid and Medicare.

The U.S. Preventive Services Task Force gave injectable PrEP an ‘A’ rating as of August 2023, and this means insurers should be covering it,” said Nunn. “However, we have found that this is not always the case; many people don't get their PrEP covered in their plans.”

Nunn is the executive director of the Rhode Island Public Health Institute (RIPHI), which led a statewide advocacy effort on this issue. “In June 2023,” she said, “the governor of RI signed a bill into law at RIPHI’s clinic, Open Door Health, mandating that insurers cover all PrEP in RI, including oral and injectable PrEP. This exemplifies how we use our research to inform public health practice and policy.”

Long-lasting PrEP represents an opportunity to enhance the well-being of vulnerable populations. Nevertheless, the researchers argue that it’s necessary for insurance companies to include these options in their coverage if they are to become widely available. Additionally, health care providers should be more active in informing their patients about the safety and efficacy of PrEP injections, implants and monthly pills.  

The results of this study - which are already informing policy in Rhode Island - could potentially lead to increased awareness of these alternatives among those who need them most, marking an important advancement in the pursuit of more effective medication adherence strategies in HIV prevention.