HIV Clinical Trials FAQ

Our research studies aim to alleviate human suffering as a result of HIV. People around the globe, from doctors to statisticians to community members, are getting involved to make a difference. Volunteers are critical to this work. Below is a list of the most frequently asked questions about participating in clinical trials that we’ve heard from our community members.

Participating in HIV Research FAQ

Why do people participate in clinical trials for HIV prevention?


People join research studies for many reasons. Some are altruistic and want to give back to their community. Others have been personally impacted by HIV and want to honor a friend or loved one by getting involved in research. Whatever their reasons, scientific progress could not be made if it weren’t for study volunteers! Study volunteers make an informed decision to join a trial to help find out if a product is safe, acceptable, and effective. Anyone interested in being in a study goes through an informed consent process to make sure they understand everything about the trial, including the risks and benefits of participating, what they will need to do, and to ensure that any questions they have are answered.

Why do we need research on new products for HIV prevention when we already have PrEP, condoms, etc?


More than a decade after the first PrEP product was approved for HIV prevention, there are still over 35,000 people who contract HIV in the US every year. No single HIV prevention product will be right for everyone. Having additional options could help protect against HIV in people who are unable or reluctant to use condoms every time they have sex, or who do not want to take pills regularly to prevent HIV. Just as there are multiple choices in contraception to prevent pregnancy, having choices in HIV prevention makes it more likely that people will find a particular product that meets their needs.

Who should participate in HIV prevention research?


Anyone who cares about ending the HIV epidemic! To gather the best data about safety and efficacy, HIV prevention methods are tested among individuals from diverse populations—including those of different sexes, genders, races, ethnicities, and socioeconomic backgrounds, as well as people with different environmental factors and potential routes of HIV transmission. 

In addition, every trial is designed to answer specific research questions. Depending on the research questions, some trials may only enroll women, while others may be open to women, men, or nonbinary individuals. It is important to understand who is eligible for each study, and what research questions will be addressed in the study.

Are people paid to participate in clinical trials?


Clinical trials compensate volunteers for their time and participation. The amount of compensation varies between trials and is usually related to how long the clinic visits are and how burdensome the clinical procedures may be. Some research sites are also able to provide assistance with parking or transportation costs.

How are participants recruited?


Recruitment strategies for HIV clinical trials vary by trial purpose, location, and target population. Past recruitment strategies have included print ads, online ads, social media sites, outreach by community organizations, outreach in venues frequented by the participant population, referral by friends or health care providers, and announcements in local news media. Individuals interested in participating in a clinical trial can search for studies in their area at

What is the age limit of research participants?


The age of HIV clinical trial participants varies, depending on the specific study.  The age range of participants will be determined by the objectives of the study, combined with ethical and safety considerations.

What is the time commitment for participating in an HIV prevention study?


Each study is different, but a typical study lasts 1 to 2 years and requires 10 to 20 clinic visits. Each visit usually takes between 30 minutes and 3 hours. In general, the first few visits are longer because you are learning about the study, going through the informed consent process, and having a physical exam and blood tests to see if you are eligible to join the study. Details about the study visits are part of the informed consent process.

What are the benefits of participating in an HIV prevention trial?


The HIV and AIDS epidemic affects people from all walks of life, all around the world. It is in everyone's best interests that we find effective methods to prevent HIV for diverse populations. Participating in HIV prevention research—and encouraging others who do—helps further efforts to find effective HIV prevention methods and, ultimately, control or stop the HIV epidemic. Though we do not know whether receiving a study product would benefit a participant, we do know that being in a study might still help participants in some ways. The risk reduction counseling that participants get as part of the study may help them avoid HIV acquisition. Also, the lab tests and physical exams that participants get while in the study might detect health problems they don’t yet know about.

If I decide to participate in a study, can I change my mind later?


Yes, you can leave a study at any time without any negative consequences. You are encouraged to take your time in deciding whether to join a study, so that you feel comfortable and fully informed before you sign up. You may want to speak with your doctor, family, and friends before you decide to join.

What are the different phases of clinical trials for HIV prevention?


Clinical trials are conducted in a stepwise manner and under strict government and community oversight to protect study participants. Clinical trials for HIV prevention are carried out in phases:

Phase 1: basic safety and acceptability; conducted in a small group of people for a short period of time.

Phase 2: expanded safety and acceptability; conducted in a larger group of people (perhaps several hundred) for a longer period of time; may provide very early signs that the product could be effective. Sometimes Phase 2 trials are differentiated between Phase 2A and Phase 2B trials; Phase 2A trials answer questions about product safety while Phase 2B trials may provide early signs about a product’s effectiveness in addition to answering questions about safety.

Phase 3: long-term safety and to see if the product can prevent HIV; conducted in a group of thousands of people for a few years; to see if a product works to prevention HIV.

How long does it take to find out if a particular HIV prevention product works?


All drugs go through a lengthy development process. Before HIV prevention products are tested in people, they must go through a range of tests in the laboratory. Then, products go through a pre-clinical research phase to answer basic questions about their safety before they are tested in humans. Finally, there are a series of different studies with humans called “clinical trials” to see if the product is safe and effective. The whole product development process usually takes at least 10 years (until a new product is fully tested and available on the market).

Safety and Ethics FAQ

What are the risks of being in a clinical trial for HIV prevention?


Some of the procedures may cause discomfort or be time-consuming. It is also possible that the product being tested could cause side-effects. Every person makes their own decision about enrolling in a trial, and can choose to withdraw from the study at any time for any reason. If the clinic staff feels it is not in a participant’s best interests to continue in the trial, they will let the participant know. It is also important to understand that ethics committees and other groups work to ensure that the rights of trial participants are protected and that they are kept safe through a safety oversight process that takes place throughout the entire trial. The safety of study participants is the top concern of the research team.

Are clinical trial participants exposed to HIV from being in the trials?


No. Clinical trials sponsored by the National Institute of Allergy and Infectious Diseases do not increase your chances of being exposed to HIV. In fact, to reduce the risk of HIV for people participating in trials, everyone receives frequent HIV testing and risk reduction counseling, including information about the correct and consistent use of condoms, safer behaviors, PrEP, and routine testing and access to treatment.

If I am in an HIV prevention study, am I protected from contracting HIV?


We don’t know. You should never assume that you are protected from HIV because of your participation in a study. You should continue to practice healthy sex and limit yourself to single-use, non-shared needles to reduce your likelihood of exposure to HIV. We do not know if a study product will protect you from HIV, and you may have gotten a placebo, not the study product itself. In addition, some clinical trials are only designed to answer questions about product safety, and cannot answer the question of whether the study product is protective. If you are worried about contracting HIV, learn about ways you can protect yourself. If you decide to join a study, the clinic staff will talk with you be sure you know all of your options for HIV prevention.

How do studies protect the health and rights of participants?


Protecting the health and respecting the rights of participants are top priorities for everyone in the HIV prevention research networks funded by the US National Institute of Allergy and Infectious Diseases. Without volunteers, we would never be able to find new methods for preventing HIV.

A first step in protecting the rights of study participants is to give them information about the study before they join. This process is called informed consent. Clinic staff give people information about the study products and the study procedures, the possible risks and benefits to participants, and the rights that they have. These include the right to receive any new information about the study that could affect whether they want to stay in it, and the right to leave the study at any time.

During the study, the clinic staff monitors participants to make sure the study products are not causing any health problems. The clinic staff also asks participants about any social problems they may experience from being in the study. If a participant has a health or social problem related to being in the study, clinic staff helps them.

There are also several groups involved in protecting participants’ rights and well-being:

  • A study safety review team and an independent safety monitoring board regularly look at the health information from the study to decide whether it appears safe to continue giving the study product or the placebo.
  • An Institutional Review Board (IRB) or Ethics Committee (EC) reviews and monitors the study plan for each clinic doing the study, including the information that is given to people about the study, study progress, and health problems in participants. The IRB/EC also looks to make sure that participants’ rights are being respected.
  • The US Food & Drug Administration (FDA) also reviews the study. The FDA enforces US laws about research in humans and the use of experimental products in research. Regulatory agencies from other participating countries also review the study. These groups enforce the local laws about research in humans and the use of experimental products in research.
  • Each study clinic has a Community Advisory Board (CAB). Its members are local people who advise the researchers and bring the concerns and interests of the community and study participants to the researchers. CAB members are also part of the team that develops each study. They also help develop or review the information that is given to participants.

How do I know that the research is following local and international cultural and ethical standards?


Because of the history of unethical research in some communities, people in minority populations may be distrustful of clinical trial participation. Today's research studies in people, however, have safeguards in place to protect the safety and well-being of research participants. Participant safety is of utmost importance. Clinical trial researchers have to follow strict ethical and legal standards such as the Belmont Report, the Code of Helsinki, and others. In addition, most clinical research must follow federal laws in the US Code of Federal Regulations that protect study participants. Participants can also leave the study at any time.

All of the known or anticipated risks as well as the possibility of unknown risks are fully described as part of the informed consent process. All participants must sign a consent form before they can join the clinical trial. Participants are encouraged to ask questions before signing the consent form and discuss their potential study participation with others prior to enrollment. They are also welcome to ask questions throughout their study participation.

A clinical trial follows a carefully designed protocol, a study plan that details what researchers will do. The protocol undergoes rigorous review by several regulatory bodies, including a local Ethics Committee or Institutional Review Board.

A local group of independent experts known as an Institutional Review Board or Ethics Committee regularly reviews the clinical trial to oversee patient safety and makes sure the researchers follow the protocol.

Researchers report the results of the trial at scientific meetings, to medical journals, and to various government agencies. Participants' names are not included in any of these reports.

Side effects are reported to the study investigator, who takes any medical action needed. Side effects are also reported to study reviewers who monitor the study closely for participant safety.

Any study conducted in the United States with a research product such as an experimental HIV vaccine must be reviewed by the U.S. Food and Drug Administration for the safety of the product and the soundness of the study questions and design. Similar regulatory agencies in other countries are also involved when trials will be conducted internationally.

Does participation in HIV prevention research encourage or lead to high-risk behaviors?


There is no evidence that participation in HIV prevention research leads individuals to engage in behaviors that make them more likely to contract HIV.6 In fact, data from several trials completed to date show that risk behaviors usually decline overall, particularly during the study period when study visits are more frequent. Participants in clinical trials are continually counseled on how to reduce their likelihood of being exposed to HIV.

It is important to remember that even approved HIV prevention products are not 100% effective. Even once we have a vaccine, it may not be 100% effective. Any HIV prevention product—even one that is highly effective in preventing HIV—should be offered along with other state-of-the-art prevention tools to increase protection against HIV.

6 Bartholow, B. N., Buchbinder, S., Celum, C., Goli, V., Koblin, Beryl, Para, M., Marmor, M., Novak, R. M., Mayer, K., Creticos, C., Orozco-Cronin, P., Popovic, V., Mastro, T. D. (May 1, 2005). HIV sexual risk behavior over 36 months of follow-up in the world's first HIV vaccine efficacy trial. Journal of Acquired Immune Deficiency Syndromes, 39 (1).