Table 2

Estimates of the impact of covariates on peak anti-CSP antibody titre following the final vaccine dose
Covariate Model 1 (N = 2,659) Model 2 (N = 1,515)
Estimate (95% CI) Pvalue Estimate (95% CI) Pvalue
Children (>3 months and <5 years) 2.59 (2.27, 2.91) <0.001 2.50 (2.12, 2.87) <0.001
Infants (<3 months) - 0.49(−0.96, −0.02) 0.04 - 0.41 (−0.91, 0.09) 0.11
Adults (>18 years) - 1.33 (−1.95, −0.69) 0.002 - 1.18 (−1.87, −0.48) 0.01
log10(CSPbase)*children 0.05 (−0.04, 0.14) 0.28 - 0.03 (−0.14, 0.09) 0.66
log10(CSPbase)*infants - 0.58 (−0.76, −0.40) <0.001 - 0.48 (−0.69, −0.27) <0.001
log10(CSPbase)*adults 0.24 (0.07, 0.41) 0.006 0.30 (0.11, 0.48) 0.002
Adjuvant (AS02 versus AS01) - 0.13 (−0.20, −0.05) <0.001 - 0.12 (−0.19, −0.05) <0.001
Parasite prevalence 0.30 (−0.29, 0.89) 0.32 0.30 (−0.32, 0.93) 0.35
Doses (2 versus 3) - 0.46 (−0.57, −0.36) <0.001 - 0.47 (−0.57, −0.37) <0.001
Schedule (017 m versus 012 m) - 0.85 (−0.93, −0.77) <0.001 - 0.84 (−0.92, −0.76) <0.001
Co-administration - 0.50 (−1.04, 0.03) 0.095 - 0.52 (−1.12, 0.07) 0.13
log10(HBsbase)*children 0.05 (0.02, 0.09) 0.005
log10(HBsbase)*infants - 0.04 (−0.14, 0.05) 0.34
log10(HBsbase)*adults - 0.12 (−0.20, −0.04) 0.002

The RTS,S vaccine effect is the estimated peak anti-CSP antibody titre for a child receiving three doses of RTS,S/AS01 administered via a 0, 1, 2 month schedule without co-administration of other vaccines. The estimates presented are the regression coefficients for log10(CSPpeak/(EU/mL)) against the corresponding covariates. The pre-vaccination anti-CSP and anti-HBs antibody titres are denoted CSPbase and HBsbase, respectively. Model 1 was fitted to all phase 2 trial participants with measurements of CSPpeak and CSPbase. Model 2 extends Model 1 by investigating the dependence of peak anti-CSP antibody titre on pre-vaccination anti-HBs titre, and includes all trial participants with measurements of CSPpeak, CSPbase and HBsbase. For categorical variables regression coefficients describe the association between the relevant covariate and log10(CSPpeak). The regression coefficient for parasite prevalence indicates that an increase in prevalence from 0 to 1 is associated with an increase in log10(CSPpeak) of 0.30. CI, confidence interval; CSP, circumsporozoite protein; HBs, hepatitis B surface antibody.

White et al.

White et al. BMC Medicine 2014 12:117   doi:10.1186/s12916-014-0117-2

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