Table 2.
Determinants of immunogenicity of RTS,S
|
Primary schedule (n=2650) |
Booster dose (n=1093) |
|||
|---|---|---|---|---|
| Estimate (95% CI) | p value | Estimate (95% CI) | p value | |
| RTS,S (5–17 months): intercept | 3·01 (2·91 to 3·10) | .. | 1·36 (1·08 to 1·65) | .. |
| RTS,S (6–12 weeks) | −0·88 (−1·00 to −0·76) | <0·0001 | −0·62 (−0·07 to −0·28) | <0·0001 |
| Age (5–17 months)* | −0·015 (−0·022 to −0·009) | <0·0001 | −0·006 (−0·015 to 0·003) | 0·19 |
| Age (6–12 weeks)* | 0·022 (−0·038 to 0·081) | 0·48 | 0·085 (−0·0002 to 0·174) | 0·058 |
| HIV positive | −0·53 (−0·64 to −0·42) | <0·0001 | −0·22 (−0·51 to 0·07) | 0·136 |
| log10(CSbase; 5–17 months)† | 0·14 (0·05 to 0·24) | 0·003 | .. | .. |
| log10(CSbase; 6–12 weeks)† | −0·58 (−0·70 to −0·46) | <0·0001 | .. | .. |
| log10(CSpeak; 5–17 months)† | .. | .. | 0·42 (0·34 to 0·51) | <0·0001 |
| log10(CSpeak; 6–12 weeks)† | .. | .. | 0·17 (0·06 to 0·29) | 0·0025 |
Estimates from linear regression analyses of the effect of covariates on peak anti-circumsporozoite antibody titre after primary vaccination of RTS,S/AS01 (log10[CSpeak/(EU/mL)]) or after a booster dose (log10[CSboost/(EU/mL)]). The intercept is taken to be vaccination of a child aged 5–17 months. Trial site was included in the regression models as a random effect. Transmission intensity, sex, preterm delivery, low weight-for-age Z score, and previous cases of clinical malaria were all tested as covariates but were not significant (appendix).
*
Change associated with a 1 month change in age.
†
Change associated with a ten-fold change in titre.