About 40 million people are living with HIV (human immunodeficiency virus) or AIDS (acquired immunodeficiency syndrome). Each day, 14,000 more become infected. HIVdrugs have vastly improved the quality of life for many of these people, but they don't yet provide a cure. That's why researchers are working so hard to develop an HIV vaccine.
How Vaccines Work
A vaccine is a medical product that prevents or controls a specific infection by stimulating the body's immune system. Over the years, researchers have developed vaccines for countless diseases, including typhoid, measles, influenza, and smallpox.
Why an HIV Vaccine Doesn't Yet Exist
As many as one out of five Americans think an HIV vaccine already does exist. But nothing could be further from the truth. Across the globe, researchers at universities, drug and biotech companies, and government agencies are working very hard to make an HIV vaccine a reality. More money has been spent on finding an HIV vaccine than on any other vaccine in history.
Then, why has it taken so long to produce an HIV vaccine -- more than 20 years after discovery of the virus? In fact, developing vaccines is almost always a long process. It took 47 years, for example, to develop a polio vaccine. Developing an HIV vaccine is even more difficult. These are a few reasons why:
- The HIV virus makes copies of itself very quickly.
- Many types of HIV exist, and new types continue to arise.
- HIV has developed clever ways of "outwitting" the immune system. Consequently, none of the people infected by HIV have ever completely cleared it from their bodies.
- Scientists are still trying to understand the specific ways the immune system needs to respond to prevent HIV infection
Types of HIV Vaccines Being Tested
Two main types of HIV vaccines are currently being tested -- preventive and therapeutic.
Preventive HIV vaccines:
- Are tested in people who are HIV-negative
- Train the immune system to "recognize" and fight off HIV before it can establish infection and make the person sick
- May one day work with varying degrees of success -- by preventing infection in all, most, or some people; by blocking continued infection; or by delaying or preventing the development of AIDS
Therapeutic HIV vaccines:
- Are tested in people who are already HIV-positive but who have healthy immune systems
- Help control infection and delay the progression of the disease by stimulating the immune system to identify and kill HIV-infected cells and by preventing or limiting HIV from making copies of itself
- Are currently being tested in just a few studies
Because they don't contain live HIV, these HIV vaccines cannot give a person HIV. However, they might prompt the body to produce antibodies to HIV that would show up on a blood test.