What Are Vaccines and What Do They Do?
A vaccine—also called a “shot” or “immunization”—is a substance that teaches your body's immune system to recognize and defend against harmful viruses or bacteria.
Vaccines given before you get infected are called “preventive vaccines” or “prophylactic vaccines,” and you get them while you are healthy. This allows your body to set up defenses against those dangers ahead of time. That way, you won't get sick if you're exposed to diseases later. Preventive vaccines 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. These research efforts include two late-stage, multinational vaccine clinical trials called Imbokodo and Mosaico.
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 living with HIV achieve and maintain viral suppression by taking HIV medication daily as prescribed, they can stay healthy and have effectively no risk of sexually transmitting HIV to their partners.
In addition, others who are at high risk for HIV infection may have access to pre-exposure prophylaxis (PrEP), or ART being used to prevent HIV. Yet, unfortunately, in 2018, 37,832 people were diagnosed with HIV infection in the United States, and approximately 1.7 million people became newly infected with 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 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 get infected with 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.