IgG levels against 13-valent pneumococcal conjugate vaccine serotypes in non pneumococcal conjugate vaccine immunized healthy Japanese and intravenous immunoglobulin preparations.

No studies showed specific antibody levels against all serotypes covered by 13-valent pneumococcal conjugate vaccine (PCV13) among polyclonal intravenous immunoglobulin (IVIG) products. Our study aimed to assess whether we could expect the efficacy of IVIG therapy for invasive pneumococcal disease (IPD) and to clarify the age group which should be recommended for IVIG therapy in case of IPD. Serotype-specific immunoglobulin G (IgG) levels against PCV13 serotypes were measured in four IVIGs which were produced from Japanese donors who were not immunized with any pneumococcal conjugate vaccines (PCVs), and in the serum of 160 non-PCV immunized Japanese subjects, by enzyme-linked immunosorbent assay. The functional opsonic activities of the IVIGs against serotypes 6B and 19A were assessed by a multiplexed opsonophagocytic killing assay. Japanese infants aged <2 years had a geometric mean IgG concentration of <0.35 μg/ml against several serotypes. Serotype-specific IgG concentrations varied among IVIGs. In general, IgG antibodies against serotypes 6A, 14 and 19A were higher in each IVIG. Although opsonization indices also varied among preparations, each IVIG had the ability to opsonize both serotypes 6B and 19A. This study suggests that routine immunization with PCV is important for prevention of IPD, especially for children <2 years old and IVIGs might be effective for IPD patients.