Disclosed is a method of purifying bacterial or fungal saccharide antigen-carrier protein conjugates from a mixture comprising free carrier protein and saccharine antigen-carrier protein conjugates, said method comprises: contacting said mixture with hydroxyapatite such that the carrier protein binds to the hydroxyapatite while the conjugates do not bind； and collecting the free saccharide antigen-carrier protein conjugates, wherein said carrier protein is selected from a tetanus toxoid, a diphtheria toxoid, CRM197, one of more N.meningitidis outer membrane protein(s), one or more heat shock protein(s), one or more pertussis protein(s), one or mote cytokine(s), one or more lymphokine(s), one or more hormone(s), one or more growth factor(s), protein D of H influenzae, pneumolysin, pneumococcal surface protein PspA, one or more iron uptake protein(s), toxin A from C.difficile, toxin B from C.difficile. and/or N19 polyepitope carrier. Also disclosed a purified saccharide antigen-carrier protein conjugate when obtained by performing the method and the use of the purified saccharide antigen-carrier protein conjugate in the manufacture of a medicament for treating or preventing a bacterial or fungal infection.
