Scanning electromicrograph of an HIV-infected T cell.

Scanning electromicrograph of an HIV-infected T cell.

Credit: NIAID

HIV, or human immunodeficiency virus, is the virus that causes AIDS (Acquired Immunodeficiency Syndrome) and can be transmitted during sexual intercourse; while sharing syringes; or from mother to child during pregnancy, childbirth or breastfeeding. First identified in 1981, HIV is the cause of one of humanity’s deadliest and most persistent epidemics. Although significant progress has been made in the fight against new infections and AIDS deaths, the HIV pandemic continues around the world.

HIV attacks the immune system by destroying CD4+ T cells, a type of white blood cell that is vital to fighting off infection. The destruction of these cells can leave people living with untreated HIV vulnerable to life-threatening infections and complications. Today, effective anti-HIV medications allow people living with HIV to lead longer, healthier lives. When taken as prescribed, these daily medications, called antiretroviral therapy, will suppress blood levels of the virus to durably “undetectable,” and prevent sexual transmission of HIV. Further, researchers have developed several methods of preventing HIV acquisition, including pre-exposure prophylaxis, or PrEP, post-exposure prophylaxis, or PEP, and voluntary adult medical male circumcision.

Why Is the Study of HIV/AIDS a Priority for NIAID?

HIV remains a major public health concern on nearly every continent. HIV treatment and prevention begins with knowing one’s HIV status. If people are found to be living with HIV, effective treatments are available to help people live long, healthy lives and prevent HIV transmission to sexual partners. If HIV-negative, prevention tools are available. In addition to PrEP and PEP, a safe and effective vaccine is needed to ensure a durable end to the global pandemic. New infections are common in many areas of the world, and stigma against those affected by HIV/AIDS is pervasive. As the leading U.S. government institute for biomedical HIV/AIDS research, NIAID is committed to conducting research to prevent new infections, end HIV-related deaths and complications, and discover a cure.

How Is NIAID Addressing This Critical Topic?

NIAID researchers and grantee institutions advance understanding of disease mechanisms and cooperate to move novel HIV prevention and treatment strategies from basic research into clinical practice. With the generous help of clinical research volunteers, investigators at NIH and around the world create opportunities for the discovery, development and evaluation of technologies and tools that can play a role in thwarting HIV transmission, improving the health of people living with HIV, and ending the pandemic.

To learn about HIV/AIDS risk factors, screening, and more information on how to prevent and treat HIV, visit the Centers for Diseases Control and Prevention (CDC) HIV/AIDS site.


Preventing new HIV infections is a key step toward ending the HIV pandemic as we know it. NIAID-supported researchers have worked since the early days of AIDS in the 1980s to identify prevention tools to keep people healthy. Today, an array of prevention methods are available for use in combination or on their own, and scientists continue to work to develop and improve cutting-edge tools and techniques that can work to prevent HIV in diverse populations around the world.

Vaccine Development

Historically, vaccination has been the best method for protecting people from infectious diseases. While an array of techniques are available for preventing HIV infection, the development of a safe and effective HIV vaccine remains key to realizing a durable end to the HIV/AIDS pandemic. NIAID-supported scientists are working toward an HIV vaccine from two complementary angles: an empirical approach that quickly moves vaccine candidates into human testing, and a theoretical approach that designs vaccine candidates based on an understanding of the immune response to HIV infection.


One of NIAID’s greatest success stories is that its research led to the development of numerous antiretroviral drugs to treat HIV/AIDS, turning what was once a uniformly fatal disease into a manageable chronic condition for many. NIAID is working to find new and more effective therapeutic products, drug classes, and combinations as well as safe and effective treatments for dangerous related co-infections and complications.

Finding a Cure

NIAID is exploring therapies that suppress the amount of HIV to such low levels that an HIV-infected person would no longer need treatment because his or her immune system could keep the remaining virus in check, creating in essence a “functional cure.”

Clinical Trials

NIAID and the National Institutes of Health (NIH) conduct ongoing clinical research on HIV infection and other immunological disorders. Read more about the active clinical trials below:

HIV Testing Sites & Care Services Locator

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Content last reviewed on January 31, 2019