A vaccine comprising a pharmaceutically acceptable excipient and a mixed carrier, multivalent pneumococcal conjugate composition comprising 21 different pneumococcal capsular polysaccharide-protein conjugates, wherein each pneumococcal capsular polysaccharide-protein conjugate comprises a protein carrier conjugated to a capsular polysaccharide from a different serotype of Streptococcus pneumoniae, wherein the Streptococcus pneumoniae serotypes are selected from 1, 3, 4, 5, 6A, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 18C, 19A, 19F, 22F, 23F, and 33F,
- wherein the protein carrier is CRM197 or tetanus toxoid, and
- wherein two of the capsular polysaccharides are conjugated to tetanus toxoid and the remaining capsular polysaccharides are conjugated to CRM197, wherein the two capsular polysaccharides that are conjugated to tetanus toxoid are from serotypes 1 and 3 or serotypes 3 and 5.