Fractional Dose Tetravalent A, C, Y, W135 Meningococcal Polysaccharide Vaccine

Hypothesis: Lower doses of each A/C/Y/W135 component of the meningococcal polysaccharide vaccine could confer a similar functional immunogenic response as the dose of 50 μg currently being used, and subsequently be equally protective. The purpose of this study is to evaluate the use of fractional dose tetravalent meningococcal polysaccharide vaccine to control outbreak especially caused by N. meningitidis serogroup W135 Primary Objectives: * To measure the immunogenicity of a dose corresponding to one fifth of the amount of the licensed meningococcal A/C/Y/W135 polysaccharide vaccine, i.e. 10 μg for each component; and * To measure the immunogenicity of a dose corresponding to one tenth of the licensed meningococcal A/C/Y/W135 polysaccharide vaccine, i.e. 5 μg for each component.