The Effect of BCG Vaccination on Immune Responses in HIV-Exposed and Unexposed Infants

Background:

Each year, more than half a million babies are infected with HIV by mother-to child transmission in developing countries. Many of these babies get sick and develop HIV disease (AIDS) at a very young age. Exposure to other infectious diseases may influence this early progression to AIDS. BCG is a live tuberculosis vaccine made from cow tuberculosis. It is routinely given at birth to most babies, also to babies born to HIV-positive mothers. BCG can cause disease (BCGosis) in HIV-infected babies. More importantly, BCG may also trigger immune responses in the body that lead to the spread of the HIV virus and early progression to AIDS.

Objective(s) and Hypothesis:

The researchers will investigate whether BCG causes progression of HIV by doing a clinical trial: babies born to HIV-positive mothers will be randomly allocated to get the BCG vaccine at birth or at 14 weeks of age. In these 2 groups of babies, the researchers will compare:

• The percentage of babies who progress to HIV disease
• Blood markers of HIV disease (the amount of virus and protective white blood cells in the body)
• The body's immune response to BCG vaccine and other childhood vaccines
• The percentage of children who develop BCG scarring, BCG vaccine complications and tuberculosis.

Potential Impact:

BCG is the most widely given vaccine worldwide and is routinely given to babies born to HIV-positive mothers in developing countries. Any effect that BCG has on HIV progression in babies will have a significant public health impact in settings with a high burden of HIV disease.