Frequently Asked Questions: NIAID, NIH, U.S. DHHS

May 2005

FAQs for Potential Volunteers in HIV Vaccine Research

  1. Can I get HIV/AIDS from an investigational vaccine?

    No. You cannot get an HIV infection from the vaccine being tested. In vaccine trials, scientists create synthetic (man-made) genes. These synthetic genes make proteins that resemble those that are present in a real virus, but they do not contain the information required to cause HIV infection.

  2. Who can participate in a vaccine trial?

    Men and women of all racial/ethnic backgrounds are encouraged to volunteer. You must be in good health and must be HIV-negative (you must not be infected with HIV). For most trials, volunteers are 18 to 50 years old. There may be other requirements for your specific trial that will be explained to you.

  3. What is the time commitment for participating in a vaccine trial?

    The time commitment varies from study to study. In general, the first few visits are the longest because you are learning about the study, reviewing and completing the informed consent form, and undergoing the screening physical and tests. Each study is different, but visits will require anywhere from 30 minutes to 3 hours. A typical trial lasts between 12 and 24 months and requires between 6 and 20 visits.

  4. What side effects can I expect from the investigational vaccine?

    Typically, there are few, if any, side effects reported by vaccine trial volunteers. However, there may be short-term side effects similar to those from other vaccinations: arm soreness, fever, headache, or fatigue. The side effects usually do not last long, and participants rarely require medical intervention. The staff at the trial site are available to discuss any side effects and to advise you on treatment, if needed. Before the study, a clinician will describe all possible side effects.

  5. Are there nonmedical risks to participating in a vaccine trial?

    Some volunteers have reported that others have treated them poorly when they learned about their participation in a trial. Some people erroneously believe that a trial participant must be infected with HIV, even though volunteers must be HIV-negative to participate. On rare occasions, you may have difficulty obtaining health insurance and/or traveling outside of the country. However, there are ways to assist you with this in the rare event it happens. It is important to note that other than the study site staff, no one will be informed that you are an HIV vaccine trial volunteer unless you make the decision to tell them yourself.

  6. If I receive a study vaccination, will I test positive on an HIV test?

    The most common HIV test checks for antibodies to HIV, not for the presence of the virus itself. Investigational vaccines are designed specifically to create immunity against HIV that may include the production of antibodies. If a study vaccine causes an antibody response, it can result in a false-positive result on an HIV test. Because of this, you should limit your HIV testing strictly to the study site, so that clinicians can perform more sensitive tests that will accurately determine whether you have contracted HIV due to an actual natural exposure. Since there is no live virus in any investigational HIV vaccines, you cannot be infected with HIV or develop AIDS from the vaccine being tested. There are no medical side effects associated with having a false-positive antibody test.

  7. If I am in a vaccine study, am I protected from infection with HIV?

    You should not assume that you are protected from HIV because of your participation in a vaccine trial. You should continue to practice safe sex and limit yourself to single-use, non-shared needles. It is not known if a study vaccine will protect you from HIV, and you may have received a placebo injection, not the vaccine itself. If you think you might be exposing yourself to HIV infection, you should seek counseling to protect yourself from doing so.

  8. Will the vaccine cause me to transmit HIV?

    No. This vaccine is not made from live virus or HIV infected cells. There is no possibility that it contains live or killed whole HIV. Therefore, it is impossible to become HIV infected or develop AIDS from the investigational vaccine or to transmit the virus as a direct result of receiving the vaccine.

  9. How will you know if this vaccine works?

    At specific intervals after receiving each injection, specialized blood tests are done to see if your immune system responds to the vaccine. The results of these tests will be evaluated and compared to what researchers already know about vaccine-induced protective responses. The researchers will also compare the rate of infection in those who received the vaccine with those who received a placebo injection to determine if there is a difference. If the rate of HIV infection for those who received the vaccine is substantially lower than those who did not receive the vaccine, we will attribute it to the investigational vaccine. You will not be exposed to HIV as part of the trial at any time, and we ask you to avoid any risk that may cause you to be exposed to the virus. Specific, ongoing counseling will be available to help you stay HIV uninfected during the trial. Trials seeking to create a safe, effective vaccine are an important part of a global effort to prevent the further spread of HIV/AIDS.

  10. If I decide to participate, can I change my mind later?

    You are encouraged to take your time in coming to a decision to participate in a vaccine trial, so that you are comfortable and fully informed before enrollment. If you wish, you may want to speak with your doctor, family, and friends before you decide to participate. It is always a voluntary decision to continue in a study, and you can withdraw at any time without any negative consequences.


McCluskey MM, Alexander SB, Larkin BD, Murguia M, Wakefield S. An HIV Vaccine: As We Build It, Will They Come? Health Affairs 2005; 24(3):643-51.

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Last Updated May 23, 2005 (ere)