A team of researchers — led by Peter Andersen, at Statens Serum Institut, Denmark, and JoAnne L. Flynn, at the University of Pittsburgh School of Medicine, Pittsburgh, — has now developed a vaccine that they termed H56 that boosts the effects of vaccination with BCG in cynomolgus monkeys, reducing clinical disease and improving survival.
Importantly, the combination of vaccination with H56 and BCG prevented reactivation of latent Mycobacterium tuberculosis
infection in the cynomolgus monkeys. This is important because the majority of individuals infected with Mycobacterium tuberculosis
do not show signs of disease because the microbe is hiding in their lungs (in what is called a latent state). However, in many of these people the microbe will "awaken" from this latent state at some point in their life to cause active disease.
Andersen, Flynn, and colleagues suggest that this dual effect of H56 on vaccination with BCG — reducing clinical disease and preventing reactivation of latent infection — provide rationale for its clinical development.