Bezer, 1958). In the late 1960s, Gotschlich and his colleagues developed a purification process capable of isolating heavier antigens, and this became the basis of current polysaccharide vaccines (Gotschlich et al., 1969). These vaccines, including the Food and Drug Administration–licensed Menomune (Sanofi Pasteur, Inc.), produce a T cell–independent response and therefore are not very effective in young children and do not produce a booster effect at any age (Granoff et al., 2008). In the 1980s, researchers demonstrated that by conjugating polysaccharides to protein carriers, a T cell–dependent immune response could be induced (Anderson et al., 1985; Robbins et al., 1996). This was significant because polysaccharide vaccines do not induce T-dependent immunity (Kelly et al., 2005, 2006) and therefore do not confer lasting immunity or significant reduction of meningococcus carriage or transmission. In 2005, a tetravalent conjugate vaccine was licensed in the United States and approved for use in persons 11–55 years old (CDC, 2005).
Currently, there are two types of meningococcal vaccines available in the United States: polysaccharide and conjugate. Meningococcal polysaccharide vaccines (MPSVs) are available worldwide in bivalent (A and C) and tetravalent (A, C, W-135, and Y) formulations, but only the tetravalent MPSV4 Menomune-A/C/Y/W-135 (Sanofi Pasteur) is licensed in the United States. Menomune contains 50 µg each of lyophilized powder that is reconstituted prior to administration with sterile, pyrogen-free distilled water without preservative in the single-dose presentation and with sterile, pyrogen-free distilled water and thimerosal, a mercury derivative added as a preservative in the multidose presentation (Sanofi Pasteur, Inc., 2009). Two quadrivalent conjugate vaccines, Menectra (Sanofi Pasteur) and Menveo (Novartis Vaccines and Diagnostics) are licensed in the United States. Menectra, licensed in 2005, contains 4 µg each of the capsular polysaccharide for the four serogroups conjugated to 48 µg of diphtheria toxoid (Sanofi Pasteur, Inc., 2011). It is provided in a single-dose vial and contains no added preservative or adjuvant (Sanofi Pasteur, Inc., 2011). Menveo, licensed in 2011, is composed of 10 µg of A and 5 µg each of C, Y, and W-135 oligosaccharides covalently bonded to the CRM197 protein (Novartis Vaccines and Diagnostics, 2010). The vaccine is supplied in two single-dose vials (A and C-Y-W-135) and contains no preservative or adjuvant (Novartis Vaccines and Diagnostics, 2010).
The Advisory Committee on Immunization Practices currently recommends routine vaccination of persons 11 to 12 years of age and individuals at increased risk of meningococcal disease including college freshman living in dormitories, military recruits, and asplenic individuals (CDC, 2005). MCV4 is preferred for persons 11 to 55 years of age; however, MPSV4 is recommended for individuals between 2 and 10 years and those greater than 55 years old (CDC, 2005). In 2009, the National Immunization Survey