Women suffer the highest rates of HIV infection around the world. By participating in studies to find new, effective HIV prevention methods, you can help women everywhere.

Women suffer the highest rates of HIV infection around the world. By participating in studies to find new, effective HIV prevention methods, you can help women everywhere.

Pre-exposure prophylaxis, or PrEP, helps HIV-negative people protect themselves from getting HIV. PrEP medications work by preparing the body to block HIV before a person is exposed to it. The medication currently approved for PrEP use is a pill that is taken once a day.

But we know not everyone can take a pill every day.

This is your chance to help us understand if one pill per month can help prevent HIV.

IMPOWER 22 is studying a new monthly PrEP pill called islatravir—a small, powerful pill that could make protection against HIV much simpler. It looks very promising based on animal studies and is safe and well-tolerated in human studies. The next step is to see if it prevents HIV infection in humans. The IMPOWER 22 study will compare the efficacy and safety of monthly islatravir to daily emtricitabine/tenofovir among cisgender women.

Who can be in the IMPOWER study?

IMPOWER 22 is recruiting women aged 16 to 45 to join the study. About 4500 women will participate in this trial—about 4000 women from
sites in Africa and 500 women from sites in the United States. See if you’re in a location where the study is being done.

How does the study work?

You will be randomly chosen to be in one of 2 groups.

Group 1

Take the monthly pill (islatravir) plus a daily placebo pill.

Group 2

Take the daily emtricitabine/tenofovir pill plus a monthly placebo pill.

The placebos look exactly like islatravir or emtricitabine/tenofovir but have no active ingredients. You, the study doctor, and the study staff will not know which study treatment group you are in.

What else is important to know about IMPOWER?


You will be in this study for up to 3 years

Everyone takes medicine

Every participant will take a daily pill and a monthly pill. But only one of the pills will have the active medication


Being in this study is voluntary, and you can stop for any reason at any time

Free, monthly medical visits

You’ll have monthly appointments that will include a check-up, as well as counseling, condoms, contraception, and STI testing

Experienced care

Your health will be closely monitored by an experienced team of clinicians and counselors while you are in this study


You will be reimbursed for your study visits to offset transportation costs and expenses you incur

No guarantee

There is no guarantee that, if you are randomized to take islatravir, it will protect you against HIV

“Imagine the dream of being able to prevent HIV using an easy, discreet, convenient, once-a-month tablet becoming a reality. Let’s be the ones who make this dream a reality!”

—Dr. Pearl Selepe, Clinical Research Site Leader, The Aurum Institute

About 1000 young women are infected with HIV every day—and many of the young women who are getting infected live in Africa. We have made progress in HIV prevention but need additional prevention tools so that people have options and can choose what works best for them.

Pre-exposure prophylaxis (PrEP) is when someone takes a medication to prepare their body to block HIV before being exposed. This medication lowers the chance of that person getting infected. It’s like taking a pill to keep from getting malaria or using birth control to prevent pregnancy. It’s the same idea.

There is a PrEP pill available now (it has a couple of different names, including “emtricitabine/tenofovir” or “FTC/TDF,” also called “Truvada”), and it works very well. It is very effective in protecting against getting HIV when taken every day. Over 120 countries have adopted the World Health Organization PrEP guidelines, and access to PrEP is increasing globally. There are studies from Australia, Kenya, Uganda, and the United States that show it is possible to make an impact on the HIV epidemic on a population level if enough people get on PrEP and take it consistently.

But for some people, it is hard to take a pill daily. Maybe someone is not able to take a pill every day, or maybe they don’t want someone else finding a bottle of pills and wondering what they are for.

This is why we are looking at PrEP drugs that last longer in the body. We want to find highly effective PrEP medications that are easier for people to use than a pill every day.

This study is testing a new HIV drug, called islatravir, for PrEP. Islatravir stays in the body for at least a month, much longer than a daily pill. It remains in the body in amounts that we think could prevent HIV. The IMPOWER study will look at how well islatravir works to prevent HIV and how safe it is, compared to the PrEP pill, called emtricitabine/tenofovir (or FTC/TDF), that has been shown to be safe and effective and is being used now.

Women in the study will be seen in the study every month for up to 36 months. At each monthly visit, they will get an HIV test, a pregnancy test, and a month’s supply of FTC/TDF (or placebo, depending on what arm they are a part of), and a single dose of islatravir (or placebo). Every 3 months they will get blood tests for the kidneys and liver to learn more about the safety of these drugs.

If women become pregnant during the study, they will learn which drug they were taking, and they will be offered the choice to continue taking their assigned drug or stop their assigned drug and switch to daily oral FTC/TDF PrEP. During this time, women stay in the study and we will learn about the safety of islatravir and FTC/TDF during pregnancy. With FTC/TDF PrEP, it took several years for pregnant women to be able to access it after we knew that it worked because there was limited information about its safety in pregnancy. If islatravir works to prevent HIV and is safe to use, the data on islatravir during pregnancy that we get from IMPOWER could shorten the time from when we have results to when pregnant women could use islatravir.

If women become infected with HIV, they will stop their study drug, be tested for the amount of virus in their blood and its sensitivity to specific antiretroviral medications, and be referred for treatment of HIV. The study staff will spend time with women who become infected with HIV during the study and offer counseling and other services to help them understand and adjust to their diagnoses.

There are several partners for IMPOWER 22. Merck is the sponsor, has developed islatravir, and will work to have it approved for medical providers to prescribe if it is shown to be safe and effective. The Bill and Melinda Gates Foundation is supporting the study through a partnership with Merck and the University of Washington International Clinical Research Center (ICRC).

Yes, this study has been reviewed and approved by national drug authorities and local and national ethic and regulatory committees in the places where the study is being conducted. They looked carefully at the study design and the protection of participants like you.

An independent group of clinical research experts called the Data and Safety Monitoring Board (DSMB) review how the study is going. Importantly, the DSMB looks at the safety and efficacy data, which the study team is not allowed to see, so that the study team and investigators remain blinded to these key outcomes. The IMPOWER study will have DSMB reviews every six months. Participants will be informed if there is a change in risk in participating in the trial.

ClinicalTrials.gov is a site that lists lots of different studies. The study’s ClinicalTrials.gov Identifier number is NCT04644029 and it can be accessed online at https://clinicaltrials.gov/ct2/show/NCT04644029, and you can find even more information about IMPOWER there.

“Fewer and less frequent tablets are always easier—imagine that with HIV PrEP!”

— Margaret Kasaro, , MBChB, MSc, Research Assistant Professor, Global Women’s Health, UNC