Adjuvant formulation for mucosal administration.

A glucan comprising glucose monomers linked together in branched chains by beta-1,3 bonds and beta-1,6 linkages for use in modulating human immune responses to the viral or bacterial vaccine which is brought into contact with or administered on a mucosal surface, wherein said glucan is also administered onto a mucosal surface and wherein the glucan and the vaccine are co-administered.