HIV Overview

HIV stands for human immunodeficiency virus, which is the virus that causes HIV infection. The abbreviation “HIV” can refer to the virus or to HIV infection.

AIDS stands for acquired immunodeficiency syndrome. AIDS is the most advanced stage of HIV infection.

HIV attacks and destroys the infection-fighting CD4 cells (CD4 T lymphocyte) of the immune system. The loss of CD4 cells makes it difficult for the body to fight off infections, illnesses, and certain cancers. Without treatment, HIV can gradually destroy the immune system, causing health decline and the onset of AIDS. With treatment, the immune system can recover.

HIV can be transmitted from one person to another when certain bodily fluids are shared between people. Bodily fluids that can transmit HIV include blood, semen (“cum”), pre-seminal fluid (“pre-cum”), vaginal fluids, rectal fluids, and breastmilk. HIV can be transmitted during vaginal or anal sex, through sharing needles for injecting drugs or tattooing, by getting stuck with a needle that has the blood of someone with HIV on it, through pregnancy, and through breastfeeding.

The transmission of HIV from a birthing parent with HIV to their child during pregnancy, childbirth, or breastfeeding is called perinatal transmission of HIV. For more information on perinatal transmission, read the HIVinfo fact sheet on Preventing Perinatal Transmission of HIV.

You cannot get HIV by shaking hands or hugging a person who has HIV. You also cannot get HIV from contact with objects, such as dishes, toilet seats, or doorknobs, used by a person with HIV. HIV is not spread through the air or water or by mosquitoes, ticks, or other insects. Use the HIVinfo You Can Safely Share…With Someone With HIV infographic to spread this message.

Antiretroviral therapy (ART) is the use of HIV medicines to treat HIV infection. People on ART take a combination of HIV medicines (called an HIV treatment regimen) every day (pills) or by schedule (injections). In many cases oral medicines may be combined into a single pill or capsule. There are newer long-acting medicines given by an injection every 2 months that may be used in some people.

ART is recommended for everyone who has HIV. ART prevents HIV from multiplying, which reduces the amount of HIV in the body (called the viral load). Having less HIV in the body protects the immune system and prevents HIV infection from advancing to AIDS. ART cannot cure HIV, but HIV medicines can help people with HIV live long, healthy lives.

ART reduces the risk of HIV transmission. ART can reduce a person’s viral load to an undetectable level. An undetectable viral load means that the level of HIV in the blood is too low to be detected by a viral load test. People with HIV who maintain an undetectable viral load have no risk of transmitting HIV to their HIV-negative partner through sex.

HIV medicines taken during pregnancy, childbirth, and breastfeeding can also reduce the risk of perinatal (parent to infant) transmission of HIV. Previously, replacement feeding (properly prepared formula or pasteurized donor human milk from a milk bank) was recommended instead of breastfeeding since the risk of HIV transmission was considered high. Now, there is evidence that the risk of transmission through the breastmilk of someone consistently using ART and maintaining an undetectable viral load is low (less than 1%). Pregnant people with HIV can speak with their health care provider to determine what method of feeding their baby is right for them.

For people without HIV, there are several ways to reduce the risk of acquiring (getting) HIV infection.  Using condoms correctly with every sexual encounter, particularly with partners that are HIV positive with a detectable viral load or with partners whose HIV status is unknown, can reduce the risk of acquiring HIV. Reducing HIV risk also involves limiting and reducing sexual partners, and avoiding sharing needles.

Persons who do not have HIV should talk to their health care provider about pre-exposure prophylaxis (PrEP). PrEP is an HIV prevention option for people who do not have HIV but who are at risk of becoming infected with HIV. PrEP involves taking a specific HIV medicine every day or a long-acting injection. For more information, read the HIVinfo fact sheet on Pre-exposure Prophylaxis (PrEP).

Persons who do not have HIV, but may have been exposed to HIV, should talk to their health care provider about post-exposure prophylaxis (PEP) within 72 hours after a possible exposure. For more information, read the HIVinfo fact sheet on Post-Exposure Prophylaxis (PEP). 

To learn more about reducing the risk of HIV transmission, read the HIVinfo fact sheet The Basics of HIV Prevention. 

Within 2 to 4 weeks after infection with HIV, some people may have flu-like symptoms, such as fever, chills, or rash. The symptoms may last for a few days to several weeks. Other possible symptoms of HIV include night sweats, muscle aches, sore throat, fatigue, swollen lymph nodes, and mouth ulcers. Having these symptoms does not mean you have HIV. Other illnesses can cause the same symptoms. Some people may not feel sick during early HIV infection (called acute HIV). During this earliest stage of HIV infection, the virus multiplies rapidly. After the initial stage of infection, HIV continues to multiply but at lower levels.

More severe symptoms of HIV infection for persons not on ART may not appear for many years until HIV has developed into AIDS. People with AIDS have weakened immune systems that make them prone to opportunistic infections. Opportunistic infections are infections and infection-related cancers that occur more frequently or are more severe in people with weakened immune systems than in people with healthy immune systems.

Without treatment, HIV transmission is possible at any stage of HIV infection—even if a person with HIV has no symptoms of HIV.

Symptoms such as fever, weakness, and weight loss may be a sign that a person’s HIV has advanced to AIDS. However, a diagnosis of AIDS is based on the following criteria:

• A drop in CD4 count to less than 200 cells/mm³. A CD4 count measures the number of CD4 cells (CD4 T lymphocyte) in a sample of blood.
  
  OR
• The presence of certain opportunistic infections.

Although an AIDS diagnosis indicates severe damage to the immune system, HIV medicines can still help people at this stage of HIV infection.

From Centers for Disease Control and Prevention:

• About HIV
• AIDS and Opportunistic Infections

From the NIH Office of AIDS Research:

• Guidelines for the Use of Antiretroviral Agents in Pediatric HIV Infection: 
  • Introduction
• Recommendations for the Use of Antiretroviral Drugs During Pregnancy and Interventions to Reduce Perinatal HIV Transmission in the United States
  • Infant Feeding for Individuals with HIV in the United States

From the National Institute of Allergy and Infectious Diseases (NIAID):

• HIV/AIDS

Also see the HIV Source collection of HIV links and resources.

HIV attacks and destroys the CD4 cells (CD4 T lymphocyte) of the immune system. CD4 cells are a type of white blood cell that play a major role in protecting the body from infection. HIV uses the machinery of the CD4 cells to multiply and spread throughout the body. This process, which is carried out in seven steps or stages, is called the HIV life cycle.

Antiretroviral therapy (ART) is the use of a combination of HIV medicines to treat HIV infection. People on ART take a combination of HIV medicines (called an HIV treatment regimen) every day. HIV medicines protect the immune system by blocking HIV at different stages of the HIV life cycle. HIV medicines are grouped into different drug classes according to how they fight HIV. Each class of drugs is designed to target a specific step in the HIV life cycle.

Because an HIV treatment regimen includes HIV medicines from at least two different HIV drug classes, ART is very effective at preventing HIV from multiplying. Having less HIV in the body protects the immune system and prevents HIV from advancing to acquired immunodeficiency syndrome (AIDS).

ART cannot cure HIV, but HIV medicines help people with HIV live longer, healthier lives. HIV medicines also reduce the risk of HIV transmission (the spread of HIV to others).

The seven stages of the HIV life cycle are: 1) binding, 2) fusion, 3) reverse transcription, 4) integration, 5) replication, 6) assembly, and 7) budding.

To understand each stage in the HIV life cycle, it helps to first imagine what HIV looks like.

Now, follow each stage in the HIV life cycle as HIV attacks a CD4 cell and uses the machinery of the cell to multiply.

From the National Institute of Allergy and Infectious Diseases:

• HIV Replication Cycle
• Antiretroviral Drug Discovery and Development

Also see the HIV Source collection of HIV links and resources.

HIV Infection

Without treatment, HIV infection advances in stages, getting worse over time. HIV gradually destroys the immune system and eventually causes acquired immunodeficiency syndrome (AIDS).

There is no cure for HIV, but treatment with HIV medicines (called antiretroviral therapy or ART) can slow or prevent HIV from advancing from one stage to the next. HIV medicines help people with HIV live longer, healthier lives. One of the main goals of ART is to reduce a person's viral load to an undetectable level. An undetectable viral load means that the level of HIV in the blood is too low to be detected by a viral load test. People with HIV who maintain an undetectable viral load have effectively no risk of transmitting HIV to their HIV-negative partner through sex.

There are three stages of HIV infection:

1. Acute HIV Infection

   Acute HIV infection is the earliest stage of HIV infection, and it generally develops within 2 to 4 weeks after infection with HIV. During this time, some people have flu-like symptoms, such as fever, headache, and rash. In the acute stage of infection, HIV multiplies rapidly and spreads throughout the body. The virus attacks and destroys the infection-fighting CD4 cells (CD4 T lymphocyte) of the immune system. During the acute HIV infection stage, the level of HIV in the blood is very high, which greatly increases the risk of HIV transmission. A person may experience significant health benefits if they start ART during this stage.

2. Chronic HIV Infection

   The second stage of HIV infection is chronic HIV infection (also called asymptomatic HIV infection or clinical latency). During this stage, HIV continues to multiply in the body but at very low levels. People with chronic HIV infection may not have any HIV-related symptoms. Without ART, chronic HIV infection usually advances to AIDS in 10 years or longer, though in some people it may advance faster. People who are taking ART may be in this stage for several decades. While it is still possible to transmit HIV to others during this stage, people who take ART exactly as prescribed and maintain an undetectable viral load have effectively no risk of transmitting HIV to an HIV-negative partner through sex.

3. AIDS

   AIDS is the final, most severe stage of HIV infection. Because HIV has severely damaged the immune system, the body cannot fight off opportunistic infections. (Opportunistic infections are infections and infection-related cancers that occur more frequently or are more severe in people with weakened immune systems than in people with healthy immune systems.) People with HIV are diagnosed with AIDS if they have a CD4 count of less than 200 cells/mm3 or if they have certain opportunistic infections. Once a person is diagnosed with AIDS, they can have a high viral load and are able to transmit HIV to others very easily. Without treatment, people with AIDS typically survive about 3 years.

From HIV.gov:

• What Are HIV and AIDS?

From the Centers for Disease Control and Prevention (CDC):

• About HIV

Also see the HIV Source collection of HIV links and resources.

A latent HIV reservoir is a group of immune system cells in the body that are infected with HIV but are not actively producing new virus particles.

HIV attacks immune system cells in the body, mainly the infection-fighting CD4 cells (CD4 T lymphocytes) and uses the cells’ own machinery to make copies of itself. After HIV infects CD4 cells, it produces a large amount of viral RNA and viral proteins, and virus particles. As with most other viral infections, these infected cells that produce virus are eventually recognized as foreign to the body and destroyed by the host immune system.

However, some HIV-infected CD4 cells go into a resting or latent state. While in this resting state, the infected but latent cells do not produce new virus particles or viral products. Therefore, these cells are not recognized as infected cells by the immune system and are not destroyed. HIV can hide inside these cells for years, forming a latent HIV reservoir but, at any time, cells in the latent reservoir can become active again and start making more viruses.

To find out more about how HIV attacks cells, read the HIV Life Cycle fact sheet from HIVinfo.

HIV medicines prevent HIV from multiplying by interfering with the HIV life cycle, which reduces the amount of the virus in the body (called the viral load). Because the HIV-infected cells in a latent reservoir are not producing new copies of the virus, HIV medicines have no effect on them. 

People with HIV must take a daily combination of HIV medicines (called an HIV treatment regimen) to keep their viral loads low and to stay healthy. If a person stops taking their HIV medicines, the infected cells of the latent reservoir can begin making HIV again and the person's viral load will increase. That is why it is important to continue taking HIV medicines every day as prescribed, even when viral load levels are low.

Finding ways to target and destroy latent reservoirs is a major challenge facing HIV researchers. Researchers are exploring different strategies for destroying HIV reservoirs or making them permanently dormant, including:

• Using gene therapy (manipulating genes to treat or prevent disease) to cut out certain HIV genes and inactivate the virus in HIV-infected immune cells.
• Developing drugs or other methods to reactivate latent HIV so that the HIV can be destroyed by the immune system or new HIV therapies. This method of eliminating latent HIV reservoirs is sometimes known as the “shock and kill” or “kick and kill” strategy. Another strategy, known as “block and lock,” permanently silences all HIV reservoirs, even after treatment interruption. A substantial part of the human DNA genome contains ancient retrovirus DNA (the same type as HIV) that is permanently dormant. Researchers are hoping to develop therapeutics that activate this permanent latency in HIV.

From the National Institute of Allergy and Infectious Diseases:

• HIV/AIDS Treatment
• HIV Viral Eradication
• Sustained ART-Free HIV Remission

Also see the HIV Source collection of HIV links and resources.

Testing for HIV (human immunodeficiency virus) determines if a person has acquired HIV. HIV is the virus that causes acquired immunodeficiency syndrome (AIDS). AIDS is the most advanced stage of HIV infection.

HIV testing can detect if you have HIV, but it cannot tell how long you have had HIV or if you have AIDS.

There are two reasons why HIV testing is important:

First, an estimated 15% of people with HIV in the United States are unaware they have HIV, and it is estimated that 40% of new diagnoses of HIV are transmitted by those who are not aware of their HIV diagnosis. Knowing your HIV status can help keep you—and others—safe. 

Second, early identification of HIV is important to reduce related illnesses and improve mortality because you can get HIV treatment sooner. Early and sustained treatment will help you live a long, healthy life.

If you are HIV negative:

A negative HIV test result shows that you do not have HIV. If you are at risk, you need to continue taking steps to avoid getting HIV, such as using condoms during sex. People at risk for HIV are typically in an environment or situation where HIV is common. Examples of at-risk individuals include:

• People who have unprotected sex with multiple partners.
• Healthcare workers who may come in contact with bodily fluids.
• People who travel to areas where HIV is common (such as sub-Saharan Africa). 

If you are at high risk of getting HIV, taking medicines to prevent HIV (called pre-exposure prophylaxis or PrEP). High-risk individuals are typically engaging in activities that are known to cause HIV. Examples of high-risk individuals include:

• Men who have sex with men.
• People who inject drugs, specifically those who share needles.
• People who have regular unprotected sex with strangers (such as sex workers).

For more information, read the HIVinfo fact sheets on The Basics of HIV Prevention and Pre-Exposure Prophylaxis.

If you are HIV positive:

A positive HIV test result shows that you have HIV, but you can still take steps to protect your health and the health of your partners. Begin by talking to your health care provider about antiretroviral therapy (ART). People on ART take a combination of oral HIV medicines (pills) every day to treat HIV infection. In some cases, doctors prescribe long-acting injections to treat people with HIV. The shots are given by health care providers and require routine office visits. HIV treatment shots are given once a month or once every other month, depending on the treatment plan. ART is recommended for everyone who has HIV, and people with HIV should start ART as soon as possible. ART cannot cure HIV, but HIV medicines help people with HIV live long, healthy lives.

A main goal of ART is to reduce a person’s viral load to an undetectable level. An undetectable viral load means that the level of HIV in the blood is too low to be detected by a viral load test. People with HIV who maintain an undetectable viral load have effectively no risk of transmitting HIV to their HIV-negative partner through sex.

The Centers for Disease Control and Prevention (CDC) recommends that everyone 13 to 64 years of age get tested for HIV at least once as part of routine health care. Generally, people at higher risk for HIV should get tested each year. Sexually active gay and bisexual men may benefit from getting tested more often, such as every 3 to 6 months. If you are over 64 years of age and at risk, your health care provider may recommend HIV testing.

Factors that increase the risk of HIV include:

• Having vaginal or anal sex with someone who is HIV positive or whose HIV status you do not know.
• Injecting drugs and sharing needles, syringes, or other drug equipment with others.
• Exchanging sex for money or drugs.
• Having a sexually transmitted disease (STD), such as syphilis.
• Having sex with anyone who has any of the HIV risk factors listed above.

Talk to your health care provider about your risk for HIV and how often you should get tested for HIV.

CDC recommends that all pregnant people get tested for HIV so that they can begin taking HIV medicines if they test positive. Pregnant people with HIV take HIV medicines during pregnancy and childbirth to reduce the risk of perinatal transmission of HIV and for their own health. For more information, read the HIVinfo fact sheet on Preventing Perinatal Transmission of HIV.

There are three types of tests used to diagnose HIV infection: antibody tests, antigen/antibody tests, and nucleic acid tests (NATs). HIV antibodies are disease-fighting proteins that the body produces in response to HIV infection. NATs look for the virus in blood. Your health care provider can determine the appropriate HIV test for you.  How soon each test can detect HIV infection differs, because each test has a different window period. The window period is the time between when a person may have been exposed to HIV and when a test can accurately detect HIV infection.

• Antibody tests check for HIV antibodies in blood or oral fluid. Most rapid tests and home use self-tests are antibody tests. Generally, antibody tests that use blood from a vein can detect HIV sooner than tests done with blood from a finger stick or with oral fluid.
• Antigen/antibody tests can detect both HIV antibodies and HIV antigens (a protein of the virus) in the blood and are the most used HIV tests. After HIV exposure, antigens will show up in the blood of a recently exposed person sooner than antibodies.
• NATs look for HIV in the blood taken from a vein. These tests may also be called "viral load tests" because they not only detect the virus but also determine the quantity of virus present in the blood. They can usually find HIV as soon as 10 to 33 days after infection. They are mostly used for monitoring HIV treatment and not for routine screening because they are expensive.

A person’s initial HIV test will usually be either an antibody test or an antigen/antibody test. NATs are not routinely used for HIV screening unless the person had a high-risk exposure or a possible exposure with early symptoms of HIV infection.

When an HIV test is positive, a follow-up test will be conducted for confirmation.  Sometimes people will need to visit a health care provider to take a follow-up test using another blood sample. Other times, the follow-up test may be performed in a lab using the original blood sample to ensure that the first positive result wasn’t a false positive.

Talk to your health care provider who will determine your HIV risk factors and the best type of HIV test for you.

HIV testing can be confidential or anonymous. 

Confidential testing means that your HIV test results will include your name and other identifying information, and the results will be included in your medical record. HIV-positive test results will be reported to local or state health departments to be counted in statistical reports. Health departments remove all personal information (including names and addresses) from HIV test results before sharing the information with CDC. CDC uses this information for reporting purposes and does not share this information with any other organizations, including insurance companies.

Anonymous testing means you do not have to give your name when you take an HIV test. When you take the test, you receive a number. To get your HIV test results, you give the number instead of your name.

Your health care provider can give you an HIV test. If you feel apprehensive about talking to your personal physician or family doctor, HIV testing is also available at many hospitals, medical clinics, substance use programs, and community health centers. Use CDC's GetTested treatment locator to find an HIV testing location near you. Getting tested through a professional health care provider is recommended; however, there are HIV self-testing kits available. Rapid self-test and mail-in self-test are the two types of HIV self-tests, but state laws regarding self-testing may limit their availability in some locations. 

A rapid self-test is an oral fluid (not the same as saliva) test done entirely at home or in private. The U.S. Food and Drug Administration (FDA) has approved one rapid HIV self-test called the OraQuick In-Home HIV test. Get Information Regarding the OraQuick In-Home HIV Test on the FDA website.

A mail-in self-test requires a person to provide a blood sample from a fingerstick, which is then sent to a lab for testing.  

From CDC:

• Getting Tested for HIV
• Self-Testing

From FDA:

• Information Regarding the OraQuick In-Home HIV Test

From the National Library of Medicine:

• HIV Testing

Also see the HIV Source collection of HIV links and resources.

From FDA:

• HIV and AIDS: Medicines to Help You

From the National Library of Medicine:

• Drug information from the DailyMed website

Also see the HIV Source collection of HIV links and resources.

From FDA:

• HIV and AIDS: Medicines to Help You

From the National Library of Medicine:

• Drug information from the DailyMed website

Also see the HIV Source collection of HIV links and resources.

As defined by the U.S. Food and Drug Administration (FDA), an investigational HIV drug is an experimental drug that is being studied to determine:

• Whether it is safe and effective.

• How the drug may be used in a specific situation (adults, children, pregnant people, etc.).

• How much of the drug is needed.

• Information about the potential benefits and risks of taking the drug.

Investigational HIV drugs are studied in a series of medical research studies called clinical trials. Once an investigational HIV drug has been proven safe and effective in a clinical trial, drug sponsors formally propose the FDA approve it as a new medicine for sale and marketing in the U.S. by submitting a New Drug Application. After reviewing the clinical trials, the FDA may approve the drug for general use or sale in the United States.

Since the first antiretroviral drug was described, HIV treatment has come a long way. Today, there are over 40 FDA-approved drugs to treat HIV. Most people with HIV can live a normal life span by taking a combination of two or more HIV drugs. However, some people find it hard to remember to take their prescribed HIV medicine every day, especially if they have substance use or mental health disorders. Others develop drug-resistant strains of HIV, which means that the virus mutates so that the medications they take are no longer effective. Many times, these two factors go together: forgetting to take HIV medicines allows HIV to multiply, which increases the risk of drug resistance and, therefore, HIV treatment failure.

To fill these gaps in treatment, researchers are investigating:

• New and better HIV drugs for the treatment of heavily treatment-experienced adults with multi-drug resistant HIV infections.

• Improvement and wider availability of long-acting antiretroviral therapy, the latest innovation in HIV treatment medication (usually requiring two injections every 1 or 2 months, instead of pills every day).

• Development of new formulations of long-acting antiretroviral therapy with an autoinjector device that makes it easy and safe for patients to inject the drug themselves at home, most likely under the skin. Researchers hope that this method will increase privacy and medication adherence.

• Development of new versions of long-acting antiretroviral drugs as an “ultra-long-acting treatment and prevention” that could be injected every four months, and ultimately every six months by the end of the decade.

HIV researchers are also studying investigational vaccines to prevent HIV and treat HIV. The goal of a preventive HIV vaccine is to prevent HIV in people who do not have HIV but who may be exposed to the virus. A safe and effective HIV treatment vaccine (also called a therapeutic HIV vaccine) could prevent HIV from advancing to acquired immunodeficiency syndrome (AIDS), replace the daily use of HIV medicines, and help prevent HIV transmission. 

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

Clinical trials are conducted in phases. Each phase has a different purpose and helps researchers answer different questions about the investigational drug.

• Phase 1 trial: Initial testing in a small group of people (20–80) to evaluate the drug’s safety and to identify side effects. At this point, researchers also look for signs that the new drug or treatment is effective.
• Phase 2 trial: Testing in a larger group of people (100–300) to determine the drug’s effectiveness and to further evaluate its safety.

• Phase 3 trial: Continued testing in large groups of people (1,000–3,000) to confirm the drug’s effectiveness, monitor side effects, compare it with standard or equivalent treatments (to see if it is better than current medicines), and collect information to ensure that the investigational drug can be used safely.

  In most cases, an investigational drug must be proven effective and must show continued safety in a Phase 3 clinical trial to be considered for approval by the FDA for sale in the United States. (However, some drugs go through the FDA’s accelerated approval process and are approved before a Phase 3 clinical trial is complete.)

• Phase 4 trial: Ongoing tracking that occurs after a drug is approved by the FDA for sale in the United States. The purpose of the tracking is to seek more information about the drug’s risks, benefits, and optimal use.

For more information, read the HIVinfo HIV and AIDS Clinical Trials fact sheet.

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

• To find an HIV and AIDS clinical trial that is studying an investigational HIV drug, use the find a study search feature on ClinicalTrials.gov.

• For help with your search, call a Clinicalinfo health information specialist at 1-800-448-0440 or email HIVinfo@NIH.gov.

• You can also join ResearchMatch, which is a free, secure online tool that makes it easier for the public to become involved in clinical trials. 

In some cases, an investigational HIV drug may be available through an expanded access program (sometimes called “compassionate use”). Expanded access allows for the use of an investigational drug outside of a clinical trial to treat a person who has a serious or immediate life-threatening disease and who has no FDA-approved treatment options. Drug companies must have permission from the FDA to make an investigational drug available for expanded access. must have permission from the FDA to make an investigational drug available for expanded access.

People seeking expanded access to an investigational HIV drug should talk to their health care provider to see if they may qualify to take part in an expanded access program.

One goal of HIV research is to identify safer, more effective HIV medicines. Researchers try to make clinical trials as safe as possible. However, taking an investigational HIV drug can involve both benefits and risks. Risks may include unexpected side effects from the drug, which can be unpleasant, serious, or even life-threatening.

The benefits and possible risks of participating in a clinical trial or an expanded access program are explained to people before they decide whether to participate through a process called “informed consent.” The informed consent process involves disclosing to potential research participants all the information needed to make an informed decision about whether to participate in the clinical trial.

To find more information on an investigational HIV drug, use the Clinicalinfo Drug Database, which includes up-to-date information on many investigational HIV drugs.

From the National Institutes of Health (NIH):

• NIH Clinical Research Trials and You: The Basics

• NIH Clinical Research Trials and You: Finding a Clinical Trial

From the National Institute of Allergy and Infectious Diseases:

• HIV/AIDS

From the U.S. Food and Drug Administration (FDA):

• Understanding Investigational Drugs

• Expanded Access | Information for Patients

Also see the HIV Source collection of HIV links and resources.

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.

In 2012, a therapeutic HIV vaccine called Vacc-4x showed that it may be possible to teach the immune system to control HIV in some people with HIV and reduce their viral load. 

Researchers are developing and testing therapeutic HIV vaccines to achieve HIV remission or a functional cure. The goal is that treating people with these vaccines would 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.

In summary, researchers are exploring the use of therapeutic HIV vaccines to:

• Slow down the progress of HIV infection in people with HIV.
• Achieve HIV remission, also called a functional cure (keeping viral load suppressed without the need for ART).

As an added benefit, a therapeutic HIV vaccine may also make it less likely that a person with HIV could transmit HIV to others.

After almost four decades of research, there are currently no U.S. Food and Drug Administration (FDA)-approved therapeutic HIV vaccines. However, scientists are pursuing innovative strategies to design an HIV vaccine to prevent or treat HIV infection. You must be enrolled in a clinical trial to receive an experimental HIV vaccine (see more details below).

The goal of a preventive HIV vaccine is to prevent people from getting HIV. When available, it will be given to people who do not have HIV. To learn more, read the HIVinfo What is a Preventive HIV Vaccine? fact sheet.

A therapeutic HIV vaccine is for people who already have HIV. The goal of a therapeutic HIV vaccine is to strengthen the natural immune response to the HIV that is already in people with HIV.

An online database of clinical trials on therapeutic HIV vaccines is available from the 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.

To learn more, read the HIVinfo fact sheet on HIV and AIDS Clinical Trials.

From the National Institute of Allergy and Infectious Diseases:

• HIV Vaccine Development

• Sustained ART-Free HIV Remission

• Clinical trial of HIV vaccine begins in United States and South Africa (September 20, 2023)

From the HIV Vaccine Trials Network:

• How Vaccines Work
• HIV Vaccine Myths and Facts
• HVTN Trials

Also see the HIV Source collection of HIV links and resources.

All vaccines “teach” our immune system to recognize and effectively defend our bodies against viruses or bacteria. Examples of existing vaccines are polio, tetanus, and measles. When available, a preventive HIV vaccine will be given to people who do not have HIV, with the goal of preventing HIV infection if they are exposed to the virus. A preventive HIV vaccine will teach our immune system to protect against HIV in case we are ever exposed to the virus.

After almost four decades of research, there are currently no U.S. Food and Drug Administration (FDA)-approved preventive HIV vaccines. However, scientists are pursuing innovative strategies to design an HIV vaccine to prevent or to treat HIV infection. You must be enrolled in a clinical trial to receive an experimental HIV vaccine (see more details below).

The goal of a preventive HIV vaccine is to prevent people from getting HIV. When available, it will be given to people who do not have HIV.

A therapeutic HIV vaccine is for people who already have HIV. The goal of a therapeutic HIV vaccine is to strengthen the natural immune response to the virus that is already in people with HIV.

Researchers are exploring the use of therapeutic HIV vaccines to:

• Slow  the progression of HIV infection in people with HIV.
• Achieve HIV remission, also called a functional cure (keeping viral load suppressed without the need for antiretroviral therapy [ART]).

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

No, a person cannot get HIV from a preventive HIV vaccine. The preventive HIV vaccines being studied in clinical trials do not contain HIV. Each vaccine being tested uses a slightly different design or strategy but none of them can actually transmit 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.

Treatment options for HIV have improved a lot over the last 30 years. However, like most other medicines, 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 to different medicines.

Using condoms correctly every time and taking pre-exposure prophylaxis (PrEP) can help prevent HIV transmission.

Researchers believe a preventive HIV vaccine will be the most effective way to control or completely eliminate new HIV infections.

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. Participants can get HIV through sexual contact or from sharing drug injection equipment while they are participating in a clinical trial. As stated above, 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.

An online database of clinical trials on preventive HIV vaccines is available from the 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.

To learn more, read the HIVinfo fact sheet on HIV and AIDS Clinical Trials.

From the National Institute of Allergy and Infectious Diseases:

• HIV Vaccine Development

From the HIV Vaccine Trials Network (HVTN):

• How Vaccines Work
• HIV Vaccine Myths and Facts
• HVTN Trials

Also see the HIV Source collection of HIV links and resources.

A clinical trial is a research study in which people volunteer to help find answers to specific health questions. These studies are conducted according to a plan, called a protocol, which include—

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

Clinical trials are conducted in several phases to determine whether new medical studies 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 by the U.S. Food and Drug Administration 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:

• An interventional study tests (or tries out) an intervention—a potential drug or treatment, medical device, or procedure—in people. Interventional studies are often prospective and are specifically tailored to evaluate the direct effects of new drugs or treatments on disease.
• An observational study does not test potential treatments. Instead, researchers observe participants on their current treatment plan and track health outcomes. Observational studies (also called epidemiologic studies) are mostly retrospective.

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, such as opportunistic infections.

Participation in a clinical trial 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, pregnancy, HIV treatment history, or other medical conditions.

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.

Another benefit of participating in an HIV and AIDS clinical trial is that participants 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. 

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.

The FDA believes that obtaining a research participant's written informed consent is only part of the process. Once enrolled in a study, people continue to receive information about the study through the informed consent process.

The privacy of study volunteers is very 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.

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

• Use the find a case study search feature ClinicalTrials.gov to find HIV and AIDS studies looking for volunteer participants. 

• Call a Clinicalinfo health information specialist at 1-800-448-0440 or email 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. 

From the National Institutes of Health (NIH):

• NIH Clinical Research Trials and You: The Basics

From the National Library of Medicine:

• Learn About Clinical Studies

From the Food and Drug Administration:

• Clinical Trials: What Patients Need to Know
• Informed Consent for Clinical Trials

Also see the HIV Source collection of HIV links and resources.