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HIV Vaccines

May 22, 2018

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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 disease-causing germs like viruses 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 getting HIV. Therapeutic vaccines would allow those already living with HIV to control the virus without needing to take HIV drugs. Therapeutic vaccines are being considered as one of several strategies to cure HIV.

In a best-case situation, a preventive HIV vaccine would protect nearly everyone who receives it from getting 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' public health tools. 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.

Why Do HIV Vaccines Matter to Women?

Over 30 years into the epidemic, we still do not have many ways to protect ourselves against HIV during sex that are private, woman-controlled, and independent of our partners' agreement. Pre-exposure prophylaxis (PrEP)--a daily prescription pill a woman takes before potentially coming into contact with HIV, to prevent herself from acquiring it--is a prevention method that can be controlled by the woman taking it. But there is an urgent need for a variety of prevention options that women can choose without their partners' knowledge or consent. An effective HIV vaccine would give women this option. A woman could decide to be vaccinated against HIV. Later on she might decide to talk about the decision with her partner -- or she might not. The choice would be hers.

It is important for women to participate in large numbers in HIV vaccine studies in order to find an HIV vaccine that helps protect us. This is the only way that researchers will be able to find out whether a particular vaccine works equally well in women and men. In Africa, where women bear a larger burden of the HIV epidemic than men, only about one in five HIV vaccine trial participants is a woman. As a result, scientists are concerned that study results will point us toward vaccines that may only be effective in men.

An effective HIV vaccine could also someday be given to infants born to women living with HIV to help protect the infants from getting HIV through breast milk. This would be very useful in developing countries where feeding with formula is not possible for many women living with HIV.

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. While these therapeutic vaccines will not cure HIV, they may help people living with HIV fight the virus. They would allow people living with HIV 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. This is because all the potential vaccines only use small, synthetic (human-made) pieces of HIV. These pieces of HIV cannot cause a person to acquire HIV. However, they often cause the body to make antibodies. Antibodies are proteins that the body makes to mark HIV-infected cells for destruction. As a result, HIV-negative people who have been vaccinated against HIV need to use HIV tests that look for the actual HIV virus and not for antibodies to HIV in the bloodstream. For more information, see the "Types of HIV Tests" section in our fact sheet on HIV Testing.

Is There an HIV Vaccine?

Not yet. Today there are no effective HIV vaccines.

Are There HIV Vaccine Studies Going on Now?

Yes. As of December 1, 2016, there were over 100 ongoing clinical trials of vaccines being conducted in more than 20 countries around the world. Go to this website provided by the US National Institutes of Health (NIH) to find a searchable database of publicly and privately funded clinical trials across the globe, including those for HIV vaccines.

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.

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 fewer people got HIV who were in the group of people given the vaccine, as compared to in the group of people given the placebo.

For example, if two out of 100 people who received the vaccine got HIV, and five out of 100 people who received the placebo got HIV, 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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