Serologic Responses to ACYW135 Polysaccharide Meningococcal Vaccine in Saudi Children under 5 Years of Age

Abstract

An immunization campaign with meningococcal ACYW135 polysaccharide vaccine was conducted in 2003 by the Saudi Arabian Ministry of Health and included a study to evaluate the immune responses in children under 5 years of age in the Al Qassim region of Saudi Arabia. Children who were >24 months old were given one dose of tetravalent polysaccharide vaccine, while younger children were given two doses with an interval of 2 to 3 months. Blood samples were collected prevaccination and 1 month after the second dose for children younger than 24 months old and 1 month after the single dose for older children. Serogroup-specific antibody responses were determined by serum bactericidal antibody (SBA) assays and a tetraplex immunoglobulin G (IgG) bead assay. Significant increases in the proportions of individuals who were >24 months old with SBA titers of >8 were observed pre-to postvaccination for all serogroups. Age-dependent increases in the percentage of individuals with SBA titers of >8 1 month postvaccination were observed for each serogroup. Age-dependent increases in postvaccination IgG levels were observed for serogroup A (menA), serogroup W135 (menW), and serogroup Y (menY) but not for serogroup C (menC). Two doses of tetravalent polysaccharide vaccine in individuals who were <18 months old were poorly immunogenic for menC, menW, and menY. However, for menA, 42% of the children who were 18 months old were putatively protected with SBA titers of >8. A high percentage of subjects who were >2 years of age were putatively protected for menA; a similar level was observed for menY for children who were 4 years of age but not for younger children. However, for menC and menW poor levels of putative protection were still evident at 4 years of age.

Hyporesponsiveness and its clinical implications after vaccination with polysaccharide or glycoconjugate vaccines

“…MenA-PS vaccination induces short-lived immune responses in children under 18 months of age [63,64]; however, it remains uncertain whether MenA-PS is capable of inducing immune memory when administered to children of this age [55,62,64]. In the Gambian study, serogroup A responses were generally of a greater magnitude, Review and an effect of previous MenA-PS exposure on responses to subsequent MenA-PS was not demonstrated (Figure 2A).…”

Meningococcal disease in the Middle East and Africa: Findings and updates from the Global Meningococcal Initiative

“…45 Three quadrivalent ACWY conjugate vaccines are now available. In Chile, MenW cases increased rapidly and a conjugate quadrivalent vaccine was introduced in 2012 for children <4 years old, with two doses for those <2 years old and one dose for those 2e4 years old.…”

Immunogenicity of Meningococcal ACYW135 Polysaccharide Vaccine in Saudi Children 5 to 9 Years of Age

“…A follow-up study was performed to assess the serologic responses of children Ͻ5 years old to meningococcal tetravalent ACYW135 polysaccharide vaccine (2). Children less than 18 months old received two doses 2 to 3 months apart, and those Ն24 months old received one dose.…”

“…Each group received one dose of Mencevax ACWY (GSK, Rixensart, Belgium), and blood samples were obtained from each child prior to and 1 month after vaccination following agreement to participate by the child's guardian. Serogroup-specific antibody responses were determined by SBA assays as previously described (11) by using the same meningococcal strains as those in the previous study of Saudi children Ͻ5 years old (2). Serogroup-specific immunoglobulin G (IgG) levels were determined using a tetraplex bead assay as previously described (9).…”