Role of BCG as Booster Vaccination

The BCG (bacillus Calmette-Guerin) vaccine is used for the protection against tuberculosis. Apart from it's protective effect against tuberculosis BCG vaccine has been shown to have non-specific effects on the innate immune system and is in epidemiological studies associated with reduced mortality due to infectious diseases. Several studies have shown that BCG can boost the effect of other vaccines. The present study aims to investigate the boosting effect of BCG on the response to typhoid fever vaccine (TFV) and to assess the non-specific effects of BCG on the innate immune system at early timepoints by vaccinating volunteers with either TFV alone or BCG followed by TFV 14 days later. The study hypothesis is that when BCG is given 14 days before typhoid fever vaccine a better vaccination result in terms of antibody production will be accomplished against typhoid fever due to the effects of BCG on the innate immune system.