Suchergebnisse

Immunological responses to vaccination can differ depending on whether the vaccine is given alone or with other vaccines. This study was a retrospective evaluation of the immunogenicity of a tetravalent meningococcal conjugate vaccine for serogroups A, C, W, and Y (MenACWY) administered alone (n = 41) or concomitantly with other vaccines (n = 279) to U.S. military personnel (mean age, 21.6 years) entering the military between 2006 and 2008. Concomitant vaccines included tetanus/diphtheria (Td), inactivated polio vaccine (IPV), hepatitis vaccines, and various influenza vaccines, among others; two vaccine groups excluded Tdap and IPV. Immune responses were evaluated in baseline and postvaccination sera for Neisseria meningitidis serogroups C and Y 1 to 12 months (mean, 4.96 months) following vaccination. Functional antibodies were measured by using a serum bactericidal antibody assay with rabbit complement (rSBA) and by measurement of serogroup-specific immunoglobulin G (IgG) antibodies. The percentage of vaccinees reaching threshold levels (IgG concentration in serum, ≥2 μg/ml; rSBA titer, ≥8) corresponding to an immunologic response was higher postvaccination than at baseline (P < 0.001). Administration of MenACWY along with other vaccines was associated with higher geometric means of IgG concentrations and rSBA titers than those measured 4.60 months after a single dose of MenACWY. In addition, higher percentages of vaccinees reached the immunological threshold (range of odds ratios [ORs], 1.5 to 21.7) and more of them seroconverted (OR range, 1.8 to 4.8) when MenACWY was administered with any other vaccine than when administered alone. Additional prospective randomized clinical trials are needed to confirm the observed differences among groups in the immune response to MenACWY when given concomitantly with other vaccines to U.S. military personnel.

Serogroup C meningococcal (MenC) disease accounts for one-third of all meningococcal cases and causes meningococcal outbreaks in the U.S. Quadrivalent meningococcal vaccine conjugated to diphtheria toxoid (MenACYWD) was recommended in 2005 for adolescents and high risk groups such as military recruits. We evaluated anti-MenC antibody persistence in U.S. military personnel vaccinated with either MenACYWD or meningococcal polysaccharide vaccine (MPSV4). Twelve hundred subjects vaccinated with MenACYWD from 2006 to 2008 or MPSV4 from 2002 to 2004 were randomly selected from the Defense Medical Surveillance System. Baseline serologic responses to MenC were assessed in all subjects; 100 subjects per vaccine group were tested during one of the following six post-vaccination time-points: 5–7, 11–13, 17–19, 23–25, 29–31, or 35–37 months. Anti-MenC geometric mean titers (GMT) were measured by rabbit complement serum bactericidal assay (rSBA) and geometric mean concentrations (GMC) by enzyme-linked immunosorbent assay (ELISA). Continuous variables were compared using the Wilcoxon rank sum test and the proportion of subjects with an rSBA titer ≥8 by chi-square. Pre-vaccination rSBA GMT was <8 for the MenACWYD group. rSBA GMT increased to 703 at 5–7 months post-vaccination and decreased by 94% to 43 at 3 years post-vaccination. GMT was significantly lower in the MenACWYD group at 5–7 months post-vaccination compared to the MPSV4 group. The percentage of MenACWYD recipients achieving an rSBA titer of ≥8 decreased from 87% at 5–7 months to 54% at 3 years. There were no significant differences between vaccine groups in the proportion of subjects with a titer of ≥8 at any time-point. GMC for the MenACWYD group was 0.14 µg/mL at baseline, 1.07 µg/mL at 5–7 months, and 0.66 µg/mL at 3 years, and significantly lower than the MPSV4 group at all time-points. Anti-MenC responses wane following vaccination with MenACYWD; a booster dose is needed to maintain protective levels of circulating antibody.