Researchers are trying to develop an HIV vaccine, but decades after the search began, the efforts have so far come up short. Despite the slow progress, scientists are still hopeful of success.
Vaccines teach the immune system -- your body's defense against germs -- to recognize and fight off infection. They are made from the same viruses that cause disease, but the viruses are killed or weakened first so that you do not get sick.
Your body reacts to a vaccine by making substances called antibodies, which fight a specific germ. They stay in your body and give you "immunity." That means if you ever come in contact with a virus that causes the disease, your antibodies are there to protect you.
Some examples of vaccines widely used to prevent disease include those for polio, chickenpox, measles, mumps, rubella, influenza (flu), hepatitis A and B, and human papillomavirus (HPV).
Types of HIV Vaccines
There are two types of HIV vaccines that researchers are working on:
Therapeutic HIV vaccines. These are meant for people who already have HIV -- the virus that causes the disease AIDS. They're designed to prevent HIV from becoming AIDS. The hope is that they can replace daily HIV medications, keep you healthy, and stop you from passing the disease to others.
Preventive HIV vaccines. These would be given to people who do not have HIV, to prevent them from getting infected in the future.
Why We Need an HIV Vaccine
There are many treatments for HIV, but it's still important to develop vaccines. HIV drugs have side effects, are expensive, and can be hard for people in some countries to get. You can also develop a problem called "drug resistance," which means you'll need to switch to new medications when the ones you're using stop working well for you.
There are steps you can take to reduce your risk of HIV. These include:
- Lower the number of people you have sex with.
- Use a condom when you have sex.
- Take medicine every day called pre-exposure prophylaxis (PrEP), such as emtricitabine/tenofovir disoproxil fumarate (Truvada) or emtricitabine/tenofovir alafenamide (Descovy).
Even so, thousands of people in the U.S. each year are diagnosed with HIV. An HIV vaccine could help prevent HIV infection and save lives.
Why the HIV Vaccine Has Been Hard to Develop
Researchers have studied HIV vaccines for almost a quarter-century, but they have not yet found one that works. There are several reasons for this.
In general, vaccines act in similar ways to a natural infection, which means your body makes antibodies to kill the virus. But HIV doesn't seem to activate this kind of response. There are no cases of a person who is HIV-positive who developed an immune response that successfully fought the infection. Researchers are still trying to figure out how to set off the right kind of immune response for HIV.
Another stumbling block for scientists is that most vaccines use a weak or inactivated version of the germ to start your body's immune response. But that doesn't seem to work well for HIV, and a vaccine with a live virus is too risky to use.
Progress Toward a Vaccine
Despite these roadblocks, researchers believe an HIV vaccine is still possible. There are a number of promising approaches for vaccines that scientists are investigating, including:
Broadly neutralizing antibodies (bNAbs). These antibodies stop many types of HIV from entering healthy cells. While some people living with HIV naturally make them, it's usually too late to overcome the virus.
Researchers have isolated bNAbs from the blood of people with HIV. They hope to use them to develop a therapeutic vaccine. Scientists are also studying whether giving people these antibodies as shots can help prevent HIV infection.
Mosaic-based vaccine regimens. Two clinical trials are checking these vaccines, which target more strains of HIV than any others so far.
These clinical trials also include two vaccines, in what's known as a "prime-boost" combination. It's thought that using one after the other triggers a stronger anti-HIV immune response.
PrEPVacc. This HIV prevention clinical trial will look at two experimental HIV vaccine combinations to prevent infection. One combination uses the virus's own DNA to trigger an immune response, while another uses a modified smallpox virus.
More than 40 other vaccines are in early development. These are designed to make antibodies that fight the virus or increase your body's T cells, which helps you kill cells that are infected with HIV.
Thanks to all this research, there's a real chance that an HIV vaccine could become available within a decade.
