Some volunteers in HIV vaccine studies become HIV-infected during their participation in a vaccine study. HVTN 802 and HVTN 404 are studies investigating whether the immune response in people who become HIV-infected – which is due to HIV exposure during the study and not from the vaccine itself – may affect the course of HIV infection.
Some volunteers in HIV vaccine studies develop Vaccine-Induced SeroPositivity (VISP), which occurs when a person who has received a vaccine against a disease tests reactive for having the disease despite not actually having it. When your body encounters a foreign substance, like a virus or a vaccine, your immune system produces proteins called antibodies. HIV vaccines are designed to provoke immune responses – this includes causing your body to make antibodies. Standard tests for HIV detect antibodies, not virus. These common tests do not differentiate between antibodies that are the result of a vaccine and antibodies that are the result of HIV infection. VISP occurs when study participants who receive HIV vaccines test positive (seropositive) on these standard tests but are not HIV-infected. Standard tests that look for antibodies are quick, reliable and affordable. Other tests look for the virus itself, but these are expensive and not commonly used for an initial HIV test. HIV vaccine study participants need to get the right test for HIV the one that looks for the virus rather than the antibodies. Read more about VISP on our blog or visit the HIV Vaccine Trials Network VISP page.
HVTN 910 is a study to determine how long VISP lasts in participants who have received an experimental HIV vaccine.