Saccharide-protein conjugates having a new type of linker are described. The conjugates comprising the new linker are prepared from modified saccharides comprising a moiety of the formula (I): -A-N(R1)-L-M wherein: A is a bond, —C(O)— or —OC(O)— R1 is selected from H or C1-C6 alkyl L is a C1-C12 alkylene group and M is a masked aldehyde group. The new linker is especially useful for preparing conjugates of Neisseria meningitidis serogroup A saccharide. Conjugates having this new linker have improved immunogenicity compared to other types of conjugates.
