Postvaccination, seroresponse, seroprotection and hSBA GMT were all significantly higher (p < 0.001) in recipients of two doses of MenACWY-CRM than in recipients of a single dose ( Table 4 and Table 5 and Fig. 2). The purpose of this study was to assess the safety and immunogenicity of a quadrivalent vaccine, MenACWY-CRM, currently licensed for use from 11 to 55 years of age, in children 2–10 years of age in comparison with a quadrivalent vaccine (MCV4) already licensed in this younger age group. The results of the

study demonstrate that MenACWY-CRM was well tolerated and immunogenic in these young children and with a similar safety profile and favorable immunogenicity profile compared to the licensed MCV4 product. The data from this study, along with the data that supported the licensure of the vaccine in adolescents and adults, previously published data Crizotinib nmr using two or three doses in the first year of life [21] and [22] and a single-dose schedule at 12 or 18 months of age [23], now demonstrate the safety and immunogenicity of MenACWY-CRM

across the age spectrum from infancy to 55 years of age. As a result of the relatively low incidence of meninogococcal disease, studies demonstrating the efficacy of new meningococcal vaccines are impractical. Instead, licensure of new KU 57788 products is based on demonstrating noninferiority in the immune crotamiton response to the vaccine using immunological surrogates of protection [27]. Based on the landmark studies

of Goldschneider and colleagues in the 1960s [26], bactericidal activity at a serum dilution of 1:4 using human complement was correlated with protection against invasive meningococcal disease. More recently, Trotter and colleagues confirmed the inverse correlation of serum bactericidal titer (using rabbit serum and a threshold of 1:8) and incidence of invasive serogroup C meninogococcal disease in the United Kingdom prior to universal immunization [28]. However, given the variability observed with biological assays, many regulatory authorities prefer the use of a 1:8 threshold as a surrogate measurement of protection [29]. In contrast to seroprotection where one posits that the presence of a certain level of antibody will correlate with protection against invasive disease, comparative vaccine studies benefit from a more nuanced analysis. Seroresponse is a measure of an individual’s immune response to a meningococcal antigen that may provide a more complete comparative picture of vaccine response, including those populations with elevated baseline antibody titers. In this study, seroresponse was defined as the development of seroprotective antibody levels in individuals previously seronegative to the specific capsular antigen or a four fold or greater increase in antibody in individuals already seropositive to that antigen.