TABLE 5

Numbers and percentages of subjects in each vaccine group who seroconverteda

Assay and vaccine groupNo. of subjects in groupSerogroup CSerogroup Y
SC nSC%OR95% CIP valuebSCSC%OR95% CIP valueb
IgG
    Group 1 (ref group), MenACWY only4116391.0 (ref)0.00216391.0 (ref)<0.001
    Group 2, Plus Tdap only2418754.71.5–140.00717713.81.3–110.016
    Group 3, Plus 4 not Tdap/IPV10567642.81.3–5.80.00872693.41.6–7.20.001
    Group 4, Plus 4 not Tdap150113754.62.2–9.5<0.001113754.82.3–9.9<0.001
rSBA
    Group 1 (ref group), MenACWY only4119461.0 (ref)0.016c17411.0 (ref)0.042c
    Group 2, Plus Tdap only2419794.41.4–140.01215632.30.8–6.60.105
    Group 3, Plus 4 not Tdap/IPV9861621.90.9–4.00.08655561.80.9–3.80.117
    Group 4, Plus 4 not Tdap146103712.71.4–5.60.00596662.71.3–5.50.006
  • a Unadjusted logistic regressions with odds ratios are shown for the association of the MenACWY-only group and each of the other vaccine groups. Seroconversion was defined as a 2-fold increase in IgG concentration (μg/ml) or a 4-fold increase in rSBA titer (titers below the lower limit of detection were assigned a conservative titer of 4). Significant P values are in bold; the alpha was 0.05 for the significance of the parameter values within each model. Abbreviations: CI, confidence interval; IgG, immunoglobulin G; IPV, inactivated polio vaccine; MenACWY, tetravalent meningococcal conjugate vaccine A, C, W, and Y; OR, odds ratio; rSBA, rabbit complement serum bactericidal assay; ref, reference; SC n and SC%, number and percentage, respectively, of subjects who seroconverted; Tdap, tetanus-diphtheria-acellular pertussis vaccine.

  • b Overall P values for the logistic regression. This tested the null hypothesis that vaccine group was a significant predictor of seroconversion.

  • c This P value is not statistically significant with a Bonferroni adjustment to the alpha level of 0.0125. The alpha was adjusted to 0.0125 to account for the four hypothesis tests.