Methods for producing Streptococcus pneumoniae capsular polysaccharide carrier protein conjugates

A method for making a composition comprising a Streptococcus pneumoniae polysaccharide covalently linked to a carrier protein, the method comprising:

• (a) providing a first dried composition comprising activated Streptococcus pneumoniae polysaccharides from one or more Streptococcus pneumoniae serotypes and a second dried composition comprising carrier protein;
• (b) separately reconstituting the first dried composition and the second dried composition in an organic solvent and mixing to provide a first homogenous solution comprising the one or more activated polysaccharides and a second homogenous solution comprising the carrier protein, wherein the reconstituting comprises eight minutes or less and the mixing comprises 120 minutes or less;
• (c) combining the first homogenous solution with the second homogenous solution by Tee-mixing to produce a mixture;
• and
• (d) adding a reducing agent to the mixture to produce a conjugate solution comprising a carrier protein conjugated to one or more polysaccharides of the Streptococcus pneumoniae serotype;
• wherein the first and second dried compositions are prepared by a sublimative drying process comprising lyophilization or radiant energy vacuum (REV) dehydration, and wherein the sublimative drying process comprises freezing the first and second aqueous solutions in the form of cakes.