Vaccines 101

A safe and effective HIV vaccine offers our best hope for ending the HIV epidemic. Vaccines are the most effective tool we have to prevent many infectious diseases; they have been used for decades around the world, most commonly in children.

What is a vaccine?

  • A vaccine is a product that causes the immune system to protect against a disease. The immune system is your body’s disease fighting mechanism.
  • After getting a vaccine, your body is prepared to fight against a disease

How might HIV vaccines work?

  • HIV vaccines are designed to stimulate the immune system to produce antibodies (proteins that kill virus found free-floating in the blood) and/or cytotoxic lymphocytes (CTLs or “killer T cells” that destroy HIV infected cells).
  • HIV vaccines are being studied to see if they can prevent infection or slow down disease progression in people who become infected with HIV.

How are HIV vaccines tested?

  • Potential vaccine products are first tested in the laboratory and in animal models.
  • HIV vaccines under study DO NOT contain real HIV and therefore cannot cause HIV infection.
  • Studies with humans are done in three phases:
    • Phase 1 – Small number of participants. Documenting safety is the main objective.
    • Phase 2 – Larger number of participants. Measures safety and immune response/side effects.
    • Phase 3 — Hundreds to thousands of participants to see if the vaccine is safe and effective in preventing HIV infection

Are there risks in HIV vaccine studies?

  • Any vaccine can cause side effects. For the most part these are minor (for example, a sore arm or low-grade fever) and go away within a few days. We don’t know all of the risks of HIV vaccines.
  • There are other risks to being in an HIV vaccine study. Volunteers can test HIV antibody positive due to the immune system’s response to vaccination. Volunteers may experience social harms from immigration, incarceration, military, health/life insurance services and social stigmatization.
  • Before enrolling in a HIV vaccine study, our staff will review this information with you.

Would HIV vaccines eliminate the need for other ways to prevent HIV infection?

No. It is unlikely that HIV vaccines will be 100% effective.  Therefore, condoms are needed to provide protection against HIV and sexually transmitted infections. HIV vaccines could also be used in combination with other ways to prevent HIV infection such as pre-exposure prophylaxis (PrEP).