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.
