The disclosure describes compositions containing conjugates using novel linkers, bivalent polysaccharide conjugates, and methods of bivalent polysaccharide conjugation in the development of multivalent conjugate vaccines. Conjugation of capsular polysaccharides to carrier proteins is carried out using homo-bifunctional and/or hetero-bifunctional linkers of specific lengths. Incorporation of the linkers and their use in bifunctional linkers induces higher titers of functional antibodies with high avidity, eliciting higher immunologic memory, and reduced carrier protein effect. This provides immunochemically cross-reactive capsular polysaccharides wherein one or more cross-reactive capsular polysaccharides are conjugated sequentially or concurrently to carrier protein using bifunctional linkers bearing the same or different functional groups. Such a linker and the size of the capsular polysaccharides provides an effective multivalent conjugate vaccine with high antibody titers and a reduced carrier effect and results in reduction in the content of the capsular polysaccharide and protein per dose of vaccine which reduces reactogenicity.
