Immunogenicity of meningococcal polysaccharide ACWY vaccine in primary immunized or revaccinated adults.

Summary: Meningococcal polysaccharide (Men‐Ps) vaccine immunogenicity following either primary immunization or revaccination in adults was evaluated. The study population consisted of subjects who have received tetravalent Men‐Ps vaccine once (group 1) or at least twice, with a 2–6 dose range (group 2). Human leucocyte antigen (HLA)‐typing was performed by polymerase chain reaction and specific immunoglobulin (Ig)G was measured by enzyme‐linked immunosorbent assay. Nine months post‐immunization, the percentages of individuals with levels of anti‐Men‐Ps IgG ≥ 2 µg/ml were comparable in both groups, with the exception of anti‐Men‐PsW135 IgG, which were significantly higher in group 2. The percentage of subjects doubling IgG levels at 9 months was significantly higher in group 1. The high baseline anti‐Men‐Ps antibody levels negatively influenced the response to revaccination, suggesting a feedback control of specific IgG. The calculated durability of anti‐Men‐Ps IgG was 2·5–4·5 years, depending on the Men‐Ps, following a single vaccine dose. No interference by other vaccinations nor HLA alleles association with immune response were observed. This study confirms that Men‐Ps vaccine in adults is immunogenic, even when administered repeatedly, and underlines the vaccine suitability for large‐scale adult immunization programmes that the higher costs of conjugate vaccines may limit in developing countries. Meningococcal polysaccharide (Men‐Ps) vaccine immunogenicity following either primary immunization or revaccination was evaluated in adult subjects who have received tetravalent Men‐Ps vaccine once (group 1) or at least twice, with a 2–6 dose range (group 2). Nine months post‐immunization, the percentages of individuals with levels of anti‐Men‐Ps immunoglobulin (Ig)G ≥ 2 µg/ml were comparable in both groups, with the exception of anti‐Men‐PsW135 IgG, which were significantly higher in individuals receiving booster doses. This study confirms that Men‐Ps vaccine in adults is immunogenic, even when repeatedly administered, and underlines the vaccine suitability for large‐scale adult immunization programmes that the higher costs of conjugate vaccines may limit in developing countries. [ABSTRACT FROM AUTHOR]