Frequently Asked Questions


There are several terms used to describe health disparities and health equity.

Health Disparities
A health disparity is a difference in health status and health conditions between groups. No, it’s not equal. For example, the higher rates of asthma among Blacks and Latinos compared with other racial/ethnic groups.

Health Inequities
A health inequity is a systematic and unjust distribution of social, economic, and environmental conditions needed for individual and community health. This happens when the larger social structures (i.e., discrimination, lack of good jobs, an unsafe and polluted environment, and not getting quality health care) contribute to unequal health treatment and options rather than closing the gap. For example, lower access to healthcare for recent immigrants to the U.S. and other people without health insurance.

Health Equity
Health equity is the opportunity for everyone to attain his or her full health potential. Social status, income, race, gender, sexual orientation or any other factor does not affect your health or the health services you receive. For example, access to quality health care that’s sensitive to your needs and feelings, regardless of your ability to pay.

While we often hear about existing health disparities, our focus is on health inequities which may help explain them. We can then develop solutions to achieve health equity. This is how we view the world, and we want to use research to make it better for everyone!


Pre-Exposure Prophylaxis (PrEP) means HIV negative people taking anti-HIV medication daily to prevent getting HIV. PrEP has been shown to reduce new HIV infections among men, women, and people who inject drugs. PrEP can come in many forms: a pill taken orally, a vaginal or rectal gel, a vaginal ring, or a long-acting injection Truvada® (a combination of tenofovir and emtricitabine) taken as a daily oral pill is the only type of PrEP currently approved by the Food and Drug Administration (FDA) for preventing HIV.


PrEP is not an HIV vaccine—you have to keep taking it to stay protected.

PrEP is also not a cure or treatment for HIV. HIV positive people need to be treated with combinations of at least 3, not just 2, anti–HIV medications. As with PrEP, they have to keep taking these drugs daily.

PrEP does not protect against other sexually transmitted infections (STDs), like gonorrhea, chlamydia, and syphilis, which can increase your risk of getting HIV. Condoms do prevent getting these STDs.


Anti-HIV medications disrupt the replication process of HIV. When a person first becomes infected with HIV, the virus makes millions of copies of itself and eventually becomes a part of the person’s immune system. It is thought that the first few days after exposure to HIV are the most critical in preventing the virus from taking hold. PrEP can block HIV replication from occurring and prevent HIV from establishing itself in the body.


Globally, 35 million people are living with HIV/AIDS, and 2.5 million new infections happen every year. In San Francisco, if nothing changes, there will be more than 300 new infections this year—that’s about 6 new infections every week. In Alameda County, there are nearly 200 infections every year.

Vaccines are the most effective strategy for preventing the spread of infectious diseases. An effective vaccine will train the body’s immune system to fight off disease before a person is ever exposed to the real thing. For an HIV vaccine, that might prevent an HIV–negative person from getting infected, help someone who gets infected stay healthy longer, or prevent the disease from spreading.

We need an HIV vaccine to stop this epidemic, and it will take thousands of volunteers to find one.


Absolutely! HIV/AIDS is an important health issue that trans and gender non-conforming people face, especially trans women of color. We are committed to making sure that the trans and gender non-conforming community has an opportunity to get involved in HIV prevention research at every level. We have many studies that welcome trans and gender non-conforming folks.

We also welcome trans and gender non-conforming folks on our Community Advisory Group (CAG). Fill out our contact form or text/call us at (415) 355-4345 to learn about our studies or to hear more about or CAG.


We understand that cis women need HIV prevention options that fit their lifestyle and are under their control.

We recently completed several vaginal ring studies, including MTN 036, which compared vaginal rings containing the anti-HIV medication dapivirine that could be worn for one vs. three months, We also tested a 3-month vaginal ring containing a different anti-HIV medication, tenofovir in the MTN 038 study. Vaginal rings that slowly release HIV medication over weeks or months (like contraceptive rings) could be an effective alternative to a daily pill for HIV prevention (PrEP) that is easier to use and improve adherence.

There has been a lot of interest in a long-acting, injectable form of PrEP, which can be given every 1–2 months. Bridge HIV conducted a study called HPTN 077, which evaluated the safety of the long-acting injectable medication cabotegravir among HIV-negative women and men.

We also conduct a number of HIV vaccine studies in both men, women and gender non-conforming and transgender people.


No, you cannot get HIV from an HIV vaccine or any other study product we are testing. The products we are testing do not contain any whole, live, killed, or weakened HIV. Instead, these products use man–made imitations of pieces of the virus. The idea is to trick your body’s immune system into creating a response to a threat that isn’t there. Hopefully, then, if you are ever exposed to HIV, your body will know how to fight it.

Think of it like parts of a car. If someone handed you a steering wheel and some tires, you would know they were parts from a car, and you could practice steering or changing a flat. But you couldn’t use just those parts to get yourself across the Bay Bridge.


The answer depends on which study product you receive:

For non-vaccine studies, the product will not make you test positive for HIV. For even some vaccine trials, like the AMP study, you will not test positive on a standard HIV test after the study is over. (Learn more about the AMP study and why it’s different from traditional HIV vaccine studies.)

However, for the majority of our vaccine studies, if you receive the active product, you might test positive on a standard HIV test for a long period of time. The reason for testing positive is that a vaccine might cause your immune system to make antibodies against HIV. Antibodies are your body’s way of fighting infection, and if a vaccine elicits them, it is a sign that the vaccine is making an immune response. Most HIV tests look for the antibodies, rather than the virus itself. The good news is that we can absolutely tell the difference between someone who has HIV, and someone who has antibodies because of the vaccine.

The stickier part is that if you are tested at a regular HIV testing site like a free clinic or your doctor’s office, they might not know how to tell the difference between a vaccine–positive test result and an actual HIV infection. But, you can always get tested through us, and we will be able to tell you your true HIV status. We can also provide you with documentation that your positive test is due to participation in an HIV vaccine trial, and not an indication of actual HIV infection. We will also provide you with HIV testing free of charge, or arrange for appropriate testing for you if you move out of the area, for as long as you have a positive test result caused by the vaccine.

Learn more about vaccine–induced positive HIV test results.


At Bridge HIV, we conduct different types of studies and some of those involve PrEP. Several of these studies are testing new experimental PrEP medications which are on the cutting edge of HIV prevention research, while other studies are testing new ways to support people in getting access to oral Truvada® as PrEP and taking it regularly.

You can contact us to discuss our PrEP studies that are open for enrollment.

For more information about PrEP and how to access it outside of a research study, please visit PleasePrEPMe.org and OurSexualRevolution.org.


The AMP Study (also known as HVTN 704/HPTN 085) tests an experimental antibody against HIV. AMP stands for Antibody Mediated Prevention. This is the idea of “passive vaccination” or giving people antibodies directly, rather than waiting for a vaccine to train the immune system to make them. Those antibodies will then fight off HIV if that person is exposed, and will hopefully prevent HIV infection. Learn more about this exciting new direction in vaccine research.


Bridge HIV has participated in several PrEP studies enrolling men who have sex with men (MSM), including Project T (a safety study of daily oral tenofovir) and the landmark iPrEx study, which showed that daily oral Truvada® is safe and effective for HIV prevention in MSM. The results from the iPrEx study supported the FDA approval of Truvada PrEP in 2012.

There has been a lot of interest in a long-acting, injectable form of PrEP, which can be given every 1–2 months. Bridge HIV is currently conducting HPTN 083, a large study evaluating the safety and efficacy of cabotegravir compared with daily oral Truvada® in 4,500 MSM and transgender women. We were also previously involved with HPTN 077, which evaluated the safety of cabotegravir among HIV-negative women and men.

More recently, Bridge HIV has led efforts to test strategies to expand the use of PrEP in different communities and settings. We conducted The Demo Project, a PrEP demonstration project evaluating the delivery of PrEP in STD clinics and a community health center in 3 US cities. We are also collaborating with several local clinics to conduct the Stay Study, a PrEP demonstration project among transgender people in the San Francisco Bay Area.

As taking a daily pill may not suit everyone, Bridge HIV is also conducting studies to test new PrEP drugs and formulations. We participated in the HIV Prevention Trials Network HPTN 069 study testing the safety of a new oral PrEP medication, maraviroc, in MSM, and the Microbicide Trials Network MTN 017, testing a tenofovir gel applied rectally among MSM and transwomen.

We also recently completed MTN 035, a study testing the acceptability and preferences for a douche, rectal suppository, and insert in men who have sex with men and trans people.

We are also involved in vaginal ring studies for cis-women. We completed MTN 028, MTN 036, and MTN 038 studies over the last few years.


PrEP and PEP are two ways to prevent getting HIV. Post-Exposure Prophylaxis (PEP) uses three anti-HIV medications and is started within 72 hours AFTER a potential HIV exposure and then taken daily for 28 days. Pre-Exposure Prophylaxis (PrEP) uses two anti-HIV medications and is started BEFORE potential HIV exposure, then taken daily for as long as you believe that you are at risk for HIV. PrEP can be stopped if your risk changes, but you should talk with your health care provider first.


Many studies of HIV vaccines have been completed, thanks to the help of thousands of volunteers worldwide. Six of those studies were efficacy trials, testing to see whether the vaccine protected against HIV/AIDS.

In September 2009, very exciting results from a large study in Thailand showed that people who received the vaccines used in that study had 31% fewer HIV infections than those who received placebo. Although this is a modest effect, it demonstrates that developing an HIV vaccine that prevents infection is possible. Learn more about those results.

All of our vaccine studies, even those that didn’t have a protective effect, have given us insight into how to make a highly effective vaccine. Learn more about those and other studies.


The products we are testing have all been tested in animals, and many have already been tested in people as well, so we have a good idea of the most common side effects. Common side effects of the study products we are testing tend to be mild and temporary. Because these are experimental products, there may be other side effects we don’t yet know about.

More detailed information about side effects will be discussed in person at an information session for a specific study. To see if you are eligible to attend an information session, please call (628) 217-7485 to speak with our recruitment staff.


All of the HIV vaccines and other study products we use in our studies are tested in laboratories and animals before people. Only the products that look safe and promising are moved into testing with people in randomized, placebo-controlled, double–blind studies.

Randomized means that it is completely random whether a participant is assigned to get the study product or the placebo, like rolling dice or flipping a coin.

Placebo–controlled means that volunteers in the studies may receive either the study product or a placebo, like a fake shot or pill.

Double–blind means that neither the researchers nor the participants will know who received the product or the placebo until after the study is over. At the end of the study, investigators look for differences between the study product and placebo groups to see if the product was safe and effective.

Vaccines and other study products are tested in several phases. In early phases, or safety trials, a small group of people at very low risk for HIV receive product or placebo to test for side effects and other safety concerns. If a product looks safe, a larger group of people is given the product to test what might be the best dose of that product, and if the body is making a promising immune response. Then, if a product looks both safe and promising, it is moved into a large efficacy trial, where a large group of people at risk for HIV are given either product or placebo, and researchers measure whether the product is protective against HIV.

All participants are offered extensive education, so that they know which trial they are enrolling in, and that they may receive the study product or placebo. All participants receive regular risk reduction counseling and testing to help them reduce their risk for HIV. We will also link you to other prevention services, including PrEP and treatment for drug use, if you want.

In large efficacy trials, we know that even with our best risk reduction efforts and linkage to services, some people may still get infected with HIV. The key difference between participants in a trial is whether they were randomized to get the study product or the placebo. Randomization is done so that the groups of people getting study product and placebo are similar, and we’ve brought down their risk to the lowest possible level, given current tools. Because everything else about the participants is similar, any difference in HIV infections between groups is likely due to the study product.


Our studies have different sponsors depending on what kind of HIV prevention method is being tested.

At this time, all of our vaccine studies are sponsored by the HIV Vaccine Trials Network (HVTN). The HVTN is an international collaboration of scientists and educators searching for an effective and safe HIV vaccine. Support for the HVTN comes from the National Institute of Allergy and Infectious Diseases (NIAID) of the U.S. National Institutes of Health (NIH), an agency of the U.S. Department of Health and Human Services (DHHS)

The Bill and Melinda Gates Foundation also contributes to some of these trials. The HVTN and NIAID have a close, cooperative working relationship, with shared attention to the intellectual and scientific issues. The HVTN works with vaccine developers, public and private, to test promising vaccine candidates at leading research sites in 27 cities on four continents. BridgeHIV in the San Francisco Department of Public Health is one of these partner sites.


All research activities at Bridge HIV are fully in compliance with international standards of ethical protections for research studies, as well as special standards for HIV studies. We get—and pay attention to—input from our Community Advisory Group, and the UCSF Committee on Human Research oversees our studies every step of the way. We put many safeguards in place to protect your privacy.

Participant safety is always our top priority. Before enrolling, study participants go through a process of informed consent, during which they learn all of the risks, benefits, and responsibilities of study participation. We tell you everything you need to know up front.

Participants have access to study staff at all times to address any questions or concerns. Participants can withdraw from the study at any time.


We are often recruiting for more than one study at the same time. When you call us, we’ll be able to figure out which study is the best fit for you. Studies can last from several months to a few years. Generally, there are 1–2 visits per month during the first several months, and after that visits become less frequent until the study is finished. Visits are usually carried out Monday through Friday between 8am and 7pm.


Absolutely! We have a lot of volunteers who live in the East Bay and other parts of the SF Bay Area.


There’s something everyone can do to help prevent HIV:

Be an informed advocate for HIV vaccine and prevention studies, talk to your friends about them, and support participants you know.

Invite us to come and speak to your community or volunteer group about HIV vaccine and prevention studies. Call (628) 217-7400 for more information.

Become a part of our Community Advisory Group, follow us on Instagram, like us on Facebook, follow us on Twitter.


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