Vaccine Adverse Reaction clinical trials

Comparing Morbidity and Mortality Effects of Two Different Strains of BCG

Background: Investigators at Bandim Health Project (BHP, www.bandim.org) in Guinea-Bissau have shown in several randomized trials that the Bacille-Calmette-Guérin (BCG) vaccine against tuberculosis (TB) is associated with reduced mortality in the first months of life. BCG is a live attenuated vaccine, which means that it consists of active tuberculosis bacteria that are not capable of infecting a human with TB. BCG has been grown and maintained at many different laboratories all over the world using slightly different laboratory techniques. Due to the accumulation of genetic mutations in the different BCG strains, many variants of the vaccine exists today. These have different properties when it comes to immune response, side effects, protection against TB and scar formation. The BCG scar status after vaccination is a good marker for the non-specific effects of the vaccine; among BCG-vaccinated infants, those with a BCG scar have improved survival. The investigators hypothesize that the different types of BCG vary in terms of the strength of the non-specific effects and thus the impact on overall morbidity and mortality. In the trial, the investigators will compare the two most widely used BCG strains in the world, BCG-Russia and BCG-Japan, with respect to their non-specific effects on morbidity and mortality. As an addition, the investigators will study the effect of maternal BCG vaccination on the subsequent effect of BCG-vaccination in the offspring, since there are indications that the maternal BCG scar status primes for a stronger non-specific response in the offspring.