Modified capsular saccharides comprising a blocking group at a hydroxyl group position on at least one of the monosaccharide units of the corresponding native capsular saccharide, wherein the blocking group is of the formula (Ia) or (Ib): —OX—Y (Ia) or —O—R1 (Ib) wherein X is C(O), S(O) or SO2 Y is NR1R2 or R3 R1 is C1-6 alkyl substituted with 1, 2 or 3 groups independently selected from hydroxyl, sulphydryl and amine R2 is H or C1-6 alkyl and R3 is C1-6 alkyl processes for modifying a capsular saccharide with the blocking groups saccharide-protein conjugates comprising the modified capsular saccharide processes for making the saccharide-protein conjugates, pharmaceutical compositions comprising the modified capsular saccharides and/or saccharide-protein conjugates and methods and uses of the same.
