What Is HIV?

HIV (human immunodeficiency virus) is a virus that attacks cells that help the body fight infection, making a person more vulnerable to other infections and diseases. It is spread by contact with certain bodily fluids of a person with HIV, most commonly during unprotected sex (sex without a condom or HIV medicine to prevent or treat HIV), or through sharing injection drug equipment.

If left untreated, HIV can lead to the disease AIDS (acquired immunodeficiency syndrome).

The human body can’t get rid of HIV and no effective HIV cure exists. So, once you have HIV, you have it for life.

Luckily, however, effective treatment with HIV medicine (called antiretroviral therapy or ART) is available. If taken as prescribed, HIV medicine can reduce the amount of HIV in the blood (also called the viral load) to a very low level. This is called viral suppression. If a person’s viral load is so low that a standard lab can’t detect it, this is called having an undetectable viral load. People with HIV who take HIV medicine as prescribed and get and keep an undetectable viral load can live long and healthy lives and will not transmit HIV to their HIV-negative partners through sex.

In addition, there are effective methods to prevent getting HIV through sex or drug use, including pre-exposure prophylaxis (PrEP), medicine people at risk for HIV take to prevent getting HIV from sex or injection drug use, and post-exposure prophylaxis (PEP), HIV medicine taken within 72 hours after a possible exposure to prevent the virus from taking hold. Learn about other ways to prevent getting or transmitting HIV.

What Is AIDS?

AIDS is the late stage of HIV infection that occurs when the body’s immune system is badly damaged because of the virus.

In the U.S., most people with HIV do not develop AIDS because taking HIV medicine as prescribed stops the progression of the disease.

A person with HIV is considered to have progressed to AIDS when:

• the number of their CD4 cells falls below 200 cells per cubic millimeter of blood (200 cells/mm3). (In someone with a healthy immune system, CD4 counts are between 500 and 1,600 cells/mm3.) OR
• they develop one or more opportunistic infections regardless of their CD4 count.

Without HIV medicine, people with AIDS typically survive about 3 years. Once someone has a dangerous opportunistic illness, life expectancy without treatment falls to about 1 year. HIV medicine can still help people at this stage of HIV infection, and it can even be lifesaving. But people who start HIV medicine soon after they get HIV experience more benefits—that’s why HIV testing is so important.

How Do I Know If I Have HIV?

The only way to know for sure if you have HIV is to get tested. Testing is relatively simple. You can ask your health care provider for an HIV test. Many medical clinics, substance abuse programs, community health centers, and hospitals offer them too. If you test positive, you can be connected to HIV care to start treatment as soon as possible. If you test negative, you have the information you need to take steps to prevent getting HIV in the future.

To find an HIV testing location near you, use the HIV Services Locator.

HIV self-testing is also an option. Self-testing allows people to take an HIV test and find out their result in their own home or other private location. With an HIV self-test, you can get your test results within 20 minutes. You can buy an HIV self-test kit at a pharmacy or online. Some health departments or community-based organizations also provide HIV self-test kits for a reduced cost or for free. You can call your local health department or use the HIV Services Locator to find organizations that offer HIV self-test kits near you. (Contact the organization for eligibility requirements.)

Note: State laws regarding self-testing vary and may limit availability. Check with your health care provider for additional testing options.

What Are Vaccines and What Do They Do?

Vaccines are products made from very small amounts of weak or dead germs (such as viruses, bacteria, or toxins) that can cause diseases. They help your immune system fight infections faster and more effectively.

When you get a vaccine, it sparks your immune response, helping your body fight off and remember the germ so it can attack it if the germ ever invades again. And since vaccines are made of very small amounts of weak or dead germs, they won’t make you sick.

Vaccines are usually administered by a shot, but sometimes can be administered by mouth or nasal spray. They are widely used to prevent diseases like polio, chicken pox, measles, mumps, rubella, influenza (flu), hepatitis A and B, and human papillomavirus (HPV).

Is There a Vaccine to Prevent HIV?

No. There is currently no vaccine available that will prevent HIV infection or treat those who have it.

However, scientists are working to develop one. NIH is investing in multiple approaches to prevent HIV, including a safe and effective preventive HIV vaccine.

Other NIH-supported research aims to deliver additional HIV prevention options that are safe, effective, and desirable to diverse populations and scalable worldwide to help end the global pandemic.

Learn more about how the National Institute of Allergy and Infectious Diseases, part of NIH, is approaching HIV vaccine development.

Why Do We Need a Vaccine to Prevent HIV?

Today, more people living with HIV than ever before have access to life-saving treatment with HIV medicines (called antiretroviral therapy or ART), which is good for their health. When people with HIV take HIV medicine as prescribed and get and keep an undetectable viral load, they can live long and healthy lives and will not transmit HIV to their HIV-negative partners through sex. In addition, people who are HIV-negative and who are at risk for HIV infection can take pre-exposure prophylaxis (PrEP), HIV medicine used to prevent HIV. Yet, unfortunately, in 2019, an estimated 34,800 new HIV infections occurred in the United States, and approximately 1.5 million people newly acquired HIV worldwide. To control and ultimately end HIV globally, we need a powerful array of HIV prevention tools that are widely accessible to all who would benefit from them.

Vaccines historically have been the most effective means to prevent and even eradicate infectious diseases. They safely and cost-effectively prevent illness, disability, and death. Like smallpox and polio vaccines, a preventive HIV vaccine could help save millions of lives.

Developing safe, effective, and affordable vaccines that can prevent HIV infection in uninfected people is the NIH’s highest HIV research priority given its game-changing potential for controlling and ultimately ending the HIV/AIDS pandemic.

The long-term goal is to develop a safe and effective vaccine that protects people worldwide from acquiring HIV. However, even if a vaccine only protects some people who get vaccinated, or even if it provides less than total protection by reducing the risk of infection, it could still have a major impact on the rates of transmission and help control the pandemic, particularly for populations at high risk of getting HIV. A partially effective vaccine could decrease the number of people who acquire HIV, further reducing the number of people who can pass the virus on to others. By substantially reducing the number of new infections, we can stop the epidemic.

What is a preventive HIV vaccine?

A preventive HIV vaccine is given to people who do not have HIV, with the goal of preventing HIV infection in the future. The vaccine teaches the person's immune system to recognize and effectively fight HIV in case the person is ever exposed to HIV.

Are there any FDA-approved preventive HIV vaccines?

Currently, no preventive HIV vaccines have been approved by the U.S. Food and Drug Administration (FDA), but research is underway. You must be enrolled in a clinical trial to receive a preventive HIV vaccine.

How is a preventive HIV vaccine different from a therapeutic HIV vaccine?

While a preventive HIV vaccine is given to people who do not have HIV, a therapeutic HIV vaccine is given to people who already have HIV. The goal of a therapeutic HIV vaccine is to strengthen a person’s immune response to the HIV that is already in the person’s body. Researchers are exploring the use of therapeutic HIV vaccines:

• To slow down the progression of HIV infection
• To eliminate the need for antiretroviral therapy (ART) while keeping undetectable levels of HIV

To learn more, read the HIVinfo What is a Therapeutic HIV Vaccine? fact sheet.

Can a person get HIV from a preventive HIV vaccine?

No, a person cannot get HIV from a preventive HIV vaccine. The preventive HIV vaccines being studied in clinical trials do not contain HIV. Of the approximately 30,000 people who have participated in HIV vaccine studies around the world in the last 25 years, no one has gotten HIV from any of the vaccines tested.

Why is a preventive HIV vaccine important?

Treatment options for HIV have improved a lot over the last 30 years. But HIV medicines can have side effects, can be expensive, and can be hard to access in some countries. Also, some people may develop drug resistance to certain HIV medicines and then must change medicines.

Using condoms correctly and taking pre-exposure prophylaxis (PrEP) can help prevent HIV transmission. But researchers believe a preventive HIV vaccine will be the most effective way to completely end new HIV infections.

What research is being done on preventive HIV vaccines?

Some of the areas of interest being studied in clinical trials include:

• The safety of preventive vaccines.
• Whether a preventive vaccine protects against HIV infection.
• Whether a preventive vaccine controls HIV if a person gets HIV while enrolled in a study. (It is possible for someone to get HIV through sexual contact or from sharing drug injection equipment while they are participating in a clinical trial. But a person cannot get HIV from the HIV vaccine being tested.)
• The immune responses that occur in people who receive a preventive vaccine.
• Different ways of giving preventive vaccines, such as using a needle and syringe versus a needle-free device.

Where can a person get more information about clinical trials studying preventive HIV vaccines?

A list of clinical trials on preventive HIV vaccines is available from the database of ClinicalTrials.gov study summaries. Click on the title of any trial in the list to see more information about the study.

If you are interested in participating in a vaccine study, you can also contact the National Institutes of Health Vaccine Research Center by calling 866-833-LIFE (5433) or by emailing vaccines@nih.gov.

What is a therapeutic HIV vaccine?

A therapeutic HIV vaccine is a vaccine that is designed to improve the body’s immune response to HIV in a person who already has HIV.

Researchers are developing and testing therapeutic HIV vaccines to slow down the progression of HIV to acquired immunodeficiency syndrome (AIDS). The hope is that treating people with these vaccines would ideally keep HIV at undetectable levels (known as undetectable viral load) without the need for regular antiretroviral therapy (ART). ART is the recommended treatment for HIV infection and involves using a combination of different HIV medicines to prevent HIV from multiplying. Currently, a person with HIV must remain on ART to keep HIV at undetectable levels.

A therapeutic HIV vaccine may also make it less likely that a person could transmit HIV to others.

Are there any FDA-approved therapeutic HIV vaccines?

There are currently no U.S. Food and Drug Administration (FDA)-approved therapeutic HIV vaccines, but research is underway. You must be enrolled in a clinical trial to receive a therapeutic HIV vaccine.

How is a therapeutic HIV vaccine different from a preventive HIV vaccine?

A preventive HIV vaccine is given to people who do not have HIV, with the goal of preventing HIV infection in the future. The vaccine teaches the person's immune system to recognize and effectively fight HIV in case the virus ever enters the person’s body. To learn more, read the HIVinfo What is a Preventive HIV Vaccine? fact sheet.

A therapeutic HIV vaccine is given to people who already have HIV. The goal of a therapeutic HIV vaccine is to strengthen a person’s immune response to the HIV that is already in the person's body.

Where can a person get more information about clinical trials studying therapeutic HIV vaccines?

A list of clinical trials on therapeutic HIV vaccines is available from the database of ClinicalTrials.gov study summaries. Click on the title of any trial in the list to see more information about the study.

If you are interested in participating in a vaccine study, you can also contact the National Institutes of Health Vaccine Research Center by calling 866-833-LIFE (5433) or by emailing vaccines@nih.gov.

1984

HIV was identified as the cause of AIDS. U.S. HHS Secretary Margaret Heckler declared that an AIDS vaccine will be ready for testing within two years.

1987

The first HIV vaccine clinical trial opened at the National Institutes of Health (NIH) Clinical Center in Bethesda, Maryland. This Phase 1 trial enrolled 138 healthy, HIV-negative volunteers. The gp160 subunit vaccine showed no serious adverse effects.

1988

The NIAID AIDS Vaccine Evaluation Group (AVEG), the first U.S. cooperative HIV vaccine clinical trials group, began enrolling volunteers in its first trial.

1992

NIAID launched the first Phase 2 HIV vaccine clinical trial. This trial included HIV-negative volunteers with a history of high-risk behavior -- injection drug use, multiple sex partners, or sexually transmitted infections. Participants were counseled repeatedly to avoid any behaviors that put them at risk of HIV infection.

1998

The first annual HIV Vaccine Awareness Day to honor vaccine study volunteers was observed.

The first large-scale HIV vaccine trial began. VaxGen initiated a Phase 3 trial of AIDSVAX (VAX004) in North America and the Netherlands involving more than 5,400 volunteers.

1999

NIAID began the first African preventive HIV vaccine trial in Uganda.

The first large-scale HIV vaccine trial in a developing country began. VaxGen initiated a Phase 3 trial of AIDSVAX (VAX003) involving over 2,500 volunteers in Thailand.

The newly established Vaccine Research Center (VRC) was dedicated to immunization advocates Dale and Betty Bumpers.

2000

NIAID formed the HIV Vaccine Trials Network (HVTN), a network of clinical sites in the United States and abroad dedicated to developing a preventive HIV vaccine by testing and evaluating candidate vaccines in all phases of clinical trials. The network included more than 25 sites in the United States, Africa, Asia, South America, and the Caribbean.

The first African HIV vaccine trial was completed in Uganda.

2003

The U.S. and Royal Thai governments jointly initiated RV144, a Phase 3 trial to evaluate a novel HIV vaccine strategy commonly referred to as "prime-boost."

Formation of the Global HIV Vaccine Enterprise was proposed in the journal Science.

2004

Both VaxGen candidates failed to confer protection against HIV in Phase 3 trials.

2007

NIAID halted the Phase 2 Step and Phambili studies due to safety concerns.

2009

The Phase 2 HVTN 505 study was initiated to evaluate a “prime-boost” vaccine regimen developed by the VRC.

Results of the Phase 3 Thai Trial (RV144) revealed that the vaccine combination demonstrated a modest preventive effect in humans. The trial, which enrolled more than 16,000 volunteers, was the first, and to date only, large clinical study to demonstrate efficacy for an investigational HIV vaccine.

2010

VRC scientists identified two potent antibodies that neutralize most strains of HIV in the laboratory (VRC01 and VRC02).

The Pox-Protein Public-Private Partnership (P5), an international collaborative team committed to building on the modest success of RV144, was formed.

2011

HVTN 505 was expanded to include protection from HIV as primary endpoint.

2012

Additional analyses of samples from RV144 provided insight into what types of immune responses may be needed for an effective vaccine.

2013

HVTN 505 immunizations were stopped due to lack of efficacy.

2015

The Phase 1/2 HVTN 100 study, part of the P5 research endeavor, launched to test the safety of an experimental HIV vaccine regimen based upon the RV144 findings, as well as its ability to generate an immune response.

2016

NIAID launched the AMP Studies to test whether intravenous infusions of the antibody VRC01 are safe, tolerable and effective at preventing HIV infection. The trials were also designed to answer fundamental scientific questions for HIV prevention and vaccine research.

HVTN 702, part of the P5 research endeavor, launched to test whether a new version of the RV144 HIV vaccine candidate safely prevents HIV infection among adults in South Africa.

2017

NIAID and partners launched Imbokodo or HVTN 705/HPX2008, a Phase 2b proof-of-concept study evaluating the safety and efficacy of an experimental regimen based on a “mosaic” vaccine designed to induce immune responses against a wide variety of global HIV strains.

What is a clinical trial?

A clinical trial is a research study that evaluates new medical approaches in people. These approaches include:

• new medicines or new combinations of medicines
• new medical devices or surgical procedures
• new ways to use an existing medicine or device
• new ways to change behaviors to improve health

Clinical trials are conducted in several phases to determine whether new medical approaches are safe and effective in people. Results from a Phase 1 Trial, Phase 2 Trial, and Phase 3 Trial are used to determine whether a new drug should be approved for sale in the United States. Once a new drug is approved, researchers continue to track its safety in a Phase 4 Trial.

Interventional trial and observational trial are two main types of clinical trials.

What is an HIV and AIDS clinical trial?

HIV and AIDS clinical trials help researchers find better ways to prevent, detect, or treat HIV and AIDS. Every HIV medicine was first studied through clinical trials.

Examples of HIV and AIDS clinical trials include:

• studies of new medicines to prevent or treat HIV and AIDS
• studies of vaccines to prevent or treat HIV
• studies of medicines to treat infections related to HIV and AIDS

Can anyone participate in an HIV and AIDS clinical trial?

It depends on the study. Some HIV and AIDS clinical trials enroll only people who have HIV. Other studies include people who do not have HIV.

Participation in an HIV and AIDS clinical trial may also depend on other factors, such as age, gender, HIV treatment history, or other medical conditions.

What are the benefits of participating in an HIV and AIDS clinical trial?

Participating in an HIV and AIDS clinical trial can provide benefits. For example, many people participate in HIV and AIDS clinical trials, because they want to contribute to HIV and AIDS research. They may have HIV or know someone who has HIV.

People with HIV who participate in an HIV and AIDS clinical trial may benefit from new HIV medicines before they are widely available. HIV medicines being studied in clinical trials are called investigational drugs. To learn more, read the HIVinfo What is an Investigational HIV Drug? fact sheet.

Participants in clinical trials can receive regular and careful medical care from a research team that includes doctors and other health professionals. Often the medicines and medical care are free of charge.

Sometimes people get paid for participating in a clinical trial. For example, they may receive money or a gift card. They may be reimbursed for the cost of meals or transportation.

Are HIV and AIDS clinical trials safe?

Researchers try to make HIV and AIDS clinical trials as safe as possible. However, volunteering to participate in a study testing an experimental treatment for HIV can involve risks of varying degrees. Most volunteers do not experience serious side effects; however, potential side effects that may be serious or even life-threatening can occur from the treatment being studied.

Before enrolling in a clinical trial, potential volunteers learn about the study in a process called informed consent. The process includes an explanation of the possible risks and benefits of participating in the study.

Once enrolled in a study, people continue to receive information about the study through the informed consent process.

If a person decides to participate in an HIV and AIDS clinical trial, will their personal information be shared?

The privacy of study volunteers is important to everyone involved in an HIV and AIDS clinical trial. The informed consent process includes an explanation of how a study volunteer’s personal information is protected.

How can one find an HIV and AIDS clinical trial looking for volunteer participants?

There are several ways to find an HIV and AIDS clinical trial looking for volunteer participants.

• Use the find a study search feature on ClinicalTrials.gov to find HIV and AIDS studies looking for volunteer participants.
• Call a Clinical Info health information specialist at 1-800-448-0440 or email ContactUs@HIVinfo.NIH.gov.
• Join ResearchMatch, which is a free, secure online tool that makes it easier for the public to become involved in clinical trials.