Table 3.
Incidence of Episodes of Clinical Malaria Overall and by Study Year in Children Included in the 2 Groups That Received RTS,S/AS01E, According to Anti-Circumsporozoite Antibody Titer Measured in the Post-Vaccination Sample
| Anti-CSP Antibody Titer by Tercile | PYAR | Events | Rate per 1000 PYAR (95% CI) | Hazard Ratio (95% CI) | P Value |
|---|---|---|---|---|---|
| Overall | |||||
| Lowest | 246.1 | 74 | 300.7 (239.4–377.6) | [Ref] | - |
| Medium | 248.3 | 49 | 197.3 (149.1–261.1) | 0.66 (0.44–0.99) | .044 |
| Highest | 248.4 | 31 | 124.8 (87.8–177.4) | 0.43 (0.28–0.66) | <.001 |
| 2017 | |||||
| Lowest (0.95–293.5 EU/mL) | 59.4 | 12 | 202.0 (114.7–355.8) | [Ref] | - |
| Medium (297.6–570.6 EU/mL) | 61.5 | 3 | 48.7 (15.7–151.1) | 0.24 (0.07–0.90) | .034 |
| Highest (601.0–2599.1 EU/mL) | 60.1 | 2 | 33.3 (8.32–133.1) | 0.14 (0.03–0.63) | .010 |
| 2018 | |||||
| Lowest (8.2–185.6 EU/mL) | 93.0 | 26 | 279.6 (190.4–410.6) | [Ref] | - |
| Medium (188.0–381.4 EU/mL) | 91.9 | 28 | 304.5 (210.3–441.0) | 1.11 (0.62–1.99) | .72 |
| Highest (382.5–1635.4 EU/mL) | 92.6 | 17 | 183.5 (114.1–295.2) | 0.71 (0.39–1.29) | .26 |
| 2019 | |||||
| Lowest (5.3–137.3 EU/mL) | 93.7 | 36 | 384.1 (277.0–532.4) | [Ref] | - |
| Medium (137.5–263.3 EU/mL) | 94.8 | 18 | 189.8 (119.6–301.3) | 0.48 (0.25–0.90) | .022 |
| Highest (266.5–1074.5 EU/mL) | 95.7 | 12 | 125.4 (71.2–220.8) | 0.34 (0.18, 0.65) | .001 |
Cox regression models for the pooled analysis over all 3 years of the study were adjusted for study year and the age of the child. The overall analysis aggregates person-time and events for the terciles defined separately in each year and children above and below the specific threshold in each year of the study.
Abbreviations: CI, confidence interval; EU, enzyme-linked immunosorbent assay unit; PYAR, person-years at risk.