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HIV Vaccines

May 8, 2014

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HIV Vaccines

Table of Contents

What Is a Vaccine?

A vaccine is a treatment that prevents us from getting a disease. It works by teaching our immune system how to protect itself against a disease-causing germ like a virus or bacteria.

Vaccines are one of the world's most effective tools for preventing diseases. Serious illnesses like polio, smallpox, measles, and mumps have been nearly eliminated from many countries because of vaccines.

There are two types of vaccines being studied for HIV: preventive vaccines and therapeutic vaccines. Preventive vaccines are designed to keep people from being infected with HIV. Therapeutic vaccines would allow those already infected with HIV to control the virus without needing to take HIV drugs.

In a best-case situation, a preventive HIV vaccine would protect nearly everyone who receives it from being infected with HIV. But many scientists think that the first-generation HIV vaccines will provide more limited forms of protection, in which some, but not all of the people who receive the vaccine are protected against becoming infected.

It is good to remember that none of the vaccines that are currently available (e.g., those for measles, polio, chicken pox) are 100 percent protective in 100 percent of the people who receive them. Some vaccines work better in some people than in others; other vaccines only provide protection for a limited amount of time. Yet these vaccines have been very effective and are now considered 'tried and true.' Therefore, even a partially protective HIV vaccine could be a very important tool for slowing the spread of HIV. It would also help scientists develop more effective vaccines over time.

I Have HIV -- Why Do HIV Vaccines Matter to Me?

Right now, most of the potential vaccines that are being developed are designed to prevent HIV infection in HIV-negative people. However, there are also research studies testing vaccines in people living with HIV (HIV+). While these therapeutic vaccines will not cure HIV, they may help HIV+ people fight the virus. They would allow HIV+ people to control the virus while taking fewer or no HIV drugs.

Can an HIV Vaccine Cause HIV Infection?

No. Each vaccine being tested uses a slightly different design or strategy but none of them can actually cause HIV infection. This is because all the potential vaccines only use small, synthetic (human-made) pieces of HIV. It is important to know that, while HIV vaccines cannot cause infection, people who have been vaccinated against HIV and who do not have HIV infection may have antibodies for HIV in their bloodstream. Therefore, in order for people who have been vaccinated against HIV to have their HIV status properly tested, they must use viral tests rather than antibody tests. For more information, see the "Types of HIV Tests" section in The Well Project's HIV Testing article.

Is There an HIV Vaccine?

No. Today there are no effective HIV vaccines.

Are There HIV Vaccine Studies Going on Now?

Yes. There are more than 35 clinical trials of vaccines going on in over ten countries around the world.

How Are HIV Vaccines Tested?

Like all experimental medical treatments, potential HIV vaccines go through a series of safety tests—first in animals and then in small groups of people. These small studies help determine whether or not the vaccine causes any serious side effects. Only vaccines that appear to be completely safe are considered for studies in larger groups of people that test whether the vaccine works. HIV vaccines are not tested by exposing people to HIV on purpose.

Before a research study on the effectiveness of a preventive vaccine begins, scientists usually spend two or more years looking at communities where studies may take place. They gather many types of information, including how many people get HIV each year. The rate of new infections is called the incidence rate. If 100 HIV-negative people were followed for one year, and five of them got HIV by the end of the year, you would say that there was a five percent incidence rate in that group of people.

Once these numbers have been collected, people from the community are asked to enroll in the preventive vaccine study. People in the study are randomly assigned to receive either the vaccine or a placebo (an inactive substance). Neither the researchers nor the study participants know who has received the vaccine and who has received the placebo.

The people in the study are followed for a long time—usually two to three years. At the end of the study, the researchers look to see whether the incidence rate is lower in the group of people who were given the vaccine, as compared to the group of people who were given the placebo.

For example, if there was a two percent incidence rate in people who received the vaccine, and a five percent incidence rate in people who received the placebo, that might mean that the vaccine was protecting some people against HIV.

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This article was provided by The Well Project. Visit The Well Project's Web site to learn more about their resources and initiatives for women living with HIV. The Well Project shares its content with to ensure all people have access to the highest quality treatment information available. The Well Project receives no advertising revenue from or the advertisers on this site. No advertiser on this site has any editorial input into The Well Project's content.

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