Formulation, stability and immunogenicity of a trivalent pneumococcal protein vaccine formulated with aluminum salt adjuvants

► We studied the immunogenicity and stability a pneumococcal vaccine in Al adjuvants. ► Immunogenicity was significantly higher in AlO(OH) compared to AlPO4. ► Lower microenvironment pH improved the stability of the vaccine. ► Optimal immunogenicity of the trivalent vaccine was obtained with 28 μg Al/dose. ► Pretreatment of the aluminum hydroxide with phosphate improved stability.