Table 1.
Serum bactericidal activity geometric mean titers, anti-S. sonnei LPS serum IgG geometric mean concentrations, and within-group geometric mean ratios in participants of the parent study who had baseline antibody levels below the lower limit of quantification for ELISA (modified full analysis set).
| Time point | 1790GAHB | Placebo | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| N | 0.06/1 | N | 0.3/5 | N | 1.5/25 | N | 3/50 | N | 6/100 | N | Value (95% CI) | |
| Value (95% CI) | Value (95% CI) | Value (95% CI) | Value (95% CI) | Value (95% CI) | ||||||||
| Serum bactericidal activity | ||||||||||||
| Geometric mean titer | ||||||||||||
| D1 (baseline) | 5 | 50 (50;50) | 4 | 50 (50;50) | 2 | 50 (N.A.) | 4 | 50 (50;50) | 5 | 50 (50;50) | 4 | 50 (50;50) |
| D29 | 5 | 50 (50;50) | 4 | 50 (50;50) | 2 | 50 (N.A.) | 4 | 205 (13;3181) | 5 | 414 (35;4950) | 4 | 50 (50;50) |
| D57 | 5 | 50 (50;50) | 4 | 50 (50;50) | 2 | 50 (N.A.) | 4 | 225 (12;4172) | 5 | 204 (19;2248) | 4 | 50 (50;50) |
| D85 | 5 | 50 (50;50) | 4 | 78 (19;318) | 1 | 50 | 4 | 244 (13;4689) | 5 | 203 (29;1393) | 4 | 50 (50;50) |
| D225 | 5 | 50 (50;50) | 4 | 50 (50;50) | 1 | 50 | 4 | 173 (16;1916) | 5 | 154 (36;666) | 4 | 50 (50;50) |
| Geometric mean ratio | ||||||||||||
| D29/D1 | 5 | 1.00 (1.00;1.00) | 4 | 1.00 (1.00;1.00) | 2 | 1.00 (N.A.) | 4 | 4.10 (0.26;64) | 5 | 8.29 (0.69;99) | 4 | 1.00 (1.00;1.00) |
| D57/D1 | 5 | 1.00 (1.00;1.00) | 4 | 1.00 (1.00;1.00) | 2 | 1.00 (N.A.) | 4 | 4.51 (0.24;83) | 5 | 4.09 (0.37;45) | 4 | 1.00 (1.00;1.00) |
| D85/D1 | 5 | 1.00 (1.00;1.00) | 4 | 1.56 (0.38;6.35) | 1 | 1.00 | 4 | 4.89 (0.25;94) | 5 | 4.05 (0.59;28) | 4 | 1.00 (1.00;1.00) |
| D225/D1 | 5 | 1.00 (1.00;1.00) | 4 | 1.00 (1.00;1.00) | 1 | 1.00 | 4 | 3.45 (0.31;38) | 5 | 3.09 (0.71;13) | 4 | 1.00 (1.00;1.00) |
| Anti-S. sonnei LPS serum IgG antibodies* | ||||||||||||
| Geometric mean concentration (EU/mL) | ||||||||||||
| D1 (baseline) | 5 | 2.57 (2.57;2.57) | 4 | 2.57 (2.57;2.57) | 2 | 2.46 (N.A.) | 4 | 2.17 (1.78;2.65) | 5 | 2.42 (2.13;2.76) | 4 | 2.47 (2.29;2.68) |
| D29 | 5 | 2.57 (2.57;2.57) | 4 | 7.85 (0.69;89) | 2 | 17 (N.A.) | 4 | 118 (8.45;1645) | 5 | 168 (15;1859) | 4 | 2.50 (1.97;3.18) |
| D57 | 5 | 13 (3.65;49) | 4 | 15 (0.77;275) | 2 | 46 (N.A.) | 4 | 75 (3.10;1809) | 5 | 173 (21;1435) | 4 | 2.55 (2.16;3.00) |
| D85 | 5 | 34 (6.00;192) | 4 | 23 (0.66;825) | 1 | 151 | 4 | 86 (2.09;3549) | 5 | 137 (20;913) | 4 | 2.41 (1.90;3.06) |
| D225 | 5 | 11 (0.86;135) | 4 | 12 (0.35;387) | 1 | 92 | 4 | 61 (1.01;3741) | 5 | 73 (11;500) | 4 | 2.25 (1.10;4.60) |
| Geometric mean ratio | ||||||||||||
| D29/D1 | 5 | 1.00 (1.00;1.00) | 4 | 3.06 (0.27;35) | 2 | 6.83 (N.A.) | 4 | 54 (4.23;696) | 5 | 70 (5.72;845) | 4 | 1.01 (0.77;1.33) |
| D57/D1 | 5 | 5.23 (1.42;19) | 4 | 5.66 (0.30;107) | 2 | 19 (N.A.) | 4 | 34 (1.57;755) | 5 | 72 (7.94;644) | 4 | 1.03 (0.82;1.29) |
| D85/D1 | 5 | 13.00 (2.34;75) | 4 | 9.11 (0.26;322) | 1 | 61 | 4 | 40 (1.04;1516) | 5 | 56 (7.78;409) | 4 | 0.98 (0.72;1.33) |
| D225/D1 | 5 | 4.21 (0.34;53) | 4 | 4.56 (0.14;151) | 1 | 37 | 4 | 28 (0.51;1582) | 5 | 30 (4.19;216) | 4 | 0.91 (0.41;1.99) |
LPS, lipopolysaccharide; IgG, immunoglobulin G; ELISA, enzyme-linked immunosorbent assay; EU, ELISA unit; D29, 28 days post-dose 1; D57, 28 days post-dose 2; D85, 28 days post-dose 3; D225, 6 months post-dose 3; N, number of participants with available results at a specific time point; 0.06/1, group receiving 1790GAHB formulation with 0.06 µg O antigen (OAg) and 1 µg protein; 0.3/5, group receiving 1790GAHB formulation with 0.3 µg OAg and 5 µg protein; 1.5/25, group receiving 1790GAHB formulation with 1.5 µg OAg and 25 µg protein; 3/50, group receiving 1790GAHB formulation with 3 µg OAg and 50 µg protein; 6/100, group receiving 1790GAHB formulation with 6 µg OAg and 100 µg protein; Placebo, group receiving placebo; CI, confidence interval; N.A., not applicable. CIs were not calculated with N<3. Lower limit of quantification was 100 (IC50) for SBA and 3.1–4.1 EU/mL for ELISA.
*Post-hoc sub-analysis performed on a subset of participants. Anti-S. sonnei LPS serum IgG antibody responses for all study participants has been presented in the primary publication (36).