Table 2.
Summary of GMTs and seroconversion of anti-S and anti-RBD IgG antibodies – immunogenicity analysis population
| Parameter | Age group | n | SII-ChAdOx1 nCoV-19 (N=297) |
n | AZD1222 (N=98) |
||
|---|---|---|---|---|---|---|---|
| Anti-S IgG | Anti-RBD IgG | Anti-S IgG | Anti-RBD IgG | ||||
| Baseline | |||||||
| GMT (95% CI) | Overall | 297 | 95·4 (78·1–116·6) | 170·3 (146·3–198·3) | 98 | 79·4 (58·2–108·4) | 159·8 (125·3–203·7) |
| 18–59 years | 222 | 93·7 (75·3–116·7) | 169·5 (144·1, 199·4) | 72 | 70·7 (53·7–93·1) | 144·3 (117·8, 176·6) | |
| ≥60 years | 75 | 100·8 (63·1–160·8) | 172·6 (119·1, 250·1) | 26 | 109·5 (43·1–278·2) | 212·0 (99·8, 450·1) | |
| 28 days after dose 1 – day 29 (+14) | |||||||
| GMT (95% CI) | Overall | 295 | 10 131·1 (8547·7–12 007·9) | 9786·4 (8122·6–11 791·1) | 98 | 6660·8 (4836·3–9173·7) | 6311·2 (4470·1–8910·6) |
| 18–59 years | 221 | 12 040·3 (10 046·4–14 429·9) | 11929·7 (9801·7–14 519·6) | 72 | 6918·0 (4921·6–9724·3) | 6820·4 (4863·2–9565·3) | |
| ≥60 years | 74 | 6049·7 (4083·1–8963·6) | 5417·1 (3499·0–8386·8) | 26 | 5997·5 (2697·9–13 332·7) | 5090·9 (1968·3–13 167·1) | |
| Seroconversion n (%) [95% CI] | Overall | 295 | 285 (96·6) [93·9–98·4] | 279 (94·6) [91·3–96·9] | 98 | 90 (91·8) [84·5–96·4] | 87 (88·8) [80·8–94·3] |
| 18–59 years | 221 | 216 (97·7) [94·8–99·3] | 211 (95·5) [91·8–97·8] | 72 | 69 (95·8) [88·3–99·1] | 66 (91·7) [82·7–96·9] | |
| ≥60 years | 74 | 69 (93·2) [84·9–97·8] | 68 (91·9) [83·2–97·0] | 26 | 21 (80·8) [60·6–93·4] | 21 (80·8) [60·6–93·4] | |
| 28 days after dose 2 – day 57 (+14) | |||||||
| GMT (95% CI) | Overall | 293 | 30 245·6 (26 794·0–34 141·8) | 38 576·5 (33 928·5–43 861·2) | 95 | 28 558·3 (23 479·3–34 735·8) | 36 648·9 (30 007·6–44 760·2) |
| 18–59 years | 219 | 33 438·2 (29 546·0–37 843·2) | 42 618·2 (37 468·1–48476·1) | 70 | 31 385·9 (25 379·5–38 813·8) | 40 556·5 (32 883·9–50 019·2) | |
| ≥60 years | 74 | 22 474·2 (16 549·5–30 519·9) | 28 725·0 (20 571·2–40 110·8) | 25 | 21 924·1 (13 848·1–34 710·1) | 27 597·2 (16 830·9–45 250·6) | |
| Seroconversion n (%) [95% CI] | Overall | 293 | 287 (98·0) [95·6–99·2] | 284 (96·9) [94·2–98·6] | 95 | 94 (98·9) [94·3–100·0] | 93 (97·9) [92·6–99·7] |
| 18–59 years | 219 | 217 (99·1) [96·7–99·9] | 215 (98·2) [95·4–99·5] | 70 | 70 (100·0) [94·9–100·0] | 69 (98·6) [92·3–100·0] | |
| ≥60 years | 74 | 70 (94·6) [86·7–98·5] | 69 (93·2) [84·9–97·8] | 25 | 24 (96·0) [79·6–99·9] | 24 (96·0) [79·6–99·9] | |
n=number of participants with a non-missing value at the respective visit. For each vaccine, the GMT and 95% CI of anti-S and anti-RBD IgG antibodies were calculated by transforming to the original scale of log 10-transformed mean and its two-sided 95% CI limits at each visit. Seroconversion is defined as a 4-fold increase in titre from baseline. The 95% CIs for each vaccine group were calculated by using the Clopper–Pearson method.
For seroconversion, n in respective intervention column represents number of participants with seroconversion.
CI=confidence interval; GMT=geometric mean titre; IgG=immunoglobulin G; RBD=receptor-binding domain.