Table 2.
Pre and Post wave anti-spike IgG concentrations (GMC, 95% CI) in seropositive unvaccinated mothers following wave-2 (beta), wave-3 (delta) and wave-4 (omicron). Mothers have been stratified into those whose IgG increased following the wave and those whose IgG did not increase.
| Changes in antibody titres between wave 1 and wave 2 (n=174ǂ) |
Changes in antibody titres between wave 2 and wave 3 (n=176ǂ) |
Changes in antibody titres between wave 3 and wave 4 (n=163ǂ) |
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|---|---|---|---|---|---|---|
| Post Wave 1 GMCs (95% CI) | Post Wave 2 GMCs (95% CI) | Post Wave 2 GMCs (95% CI) | Post Wave 3 GMCs (95% CI) | Post Wave 3 GMCs (95% CI) | Post Wave 4 GMCs (95% CI) | |
| (a) IgG increased | n=49 | n=49 | n=104 | n=104 | n=130 | n=130 |
| S-Ancestral | 10·39 (6·56; 16·44)a | 34·16 (21·37; 54·63) | 21·34 (16·17; 28·17)c | 136·95 (95·58; 196·22) | 52·48 (39·90; 69·03)g | 755·14 (612·62; 980·79) |
| S-Beta | 4·34 (2·70; 6·96)b | 20·80 (12·75; 33·94) | 16·10 (11·81; 21·96)d | 107·28 (73·48; 156·62) | 43·73 (33·04; 57·87)h | 552·45 (431·23; 707·75) |
| S-Delta | 4·10 (2·54; 6·63) | 14·88 (9·20; 24·07) | 9·33 (6·89; 12·64) | 94·61 (64·11; 139·62) | 40·06 (29·76; 53·92)i | 494·51 (388·30; 629·77) |
| S-Omicron | 2·16 (1·43; 3·26) | 6·64 (4·13; 10·66) | 4·18 (3·13; 5·57) | 37·54 (26·14; 53·91)e | 14·83 (11·38; 19·33)j | 303·83 (234·46; 393·71) |
| (b) IgG did not increase | n=125 | n=125 | n=72 | n=72 | n=33 | n=33 |
| S-Ancestral | 46·94 (35·70; 61·73)a | 24·44 (18·15; 32·92) | 37·35 (26·34; 52·95)c | 24·95 (17·84; 34·90) | 186·49 (94·48; 368·12)g | 91·22 (43·70; 190·42) |
| S-Beta | 22·66 (17·31; 29·67)b | 13·77 (10·45; 18·16) | 26·52 (18·04; 38·98)d | 22·30 (16·04; 31·01) | 147·68 (73·07; 298·46)h | 66·05 (32·92; 132·55) |
| S-Delta | 17·18 (13·07; 22·59) | 12·88 (9·75; 17·02) | 18·00 (12·69; 25·53) | 17·74 (13·17; 23·90) | 149·85 (76·00; 295·48)i | 63·11 (30·72; 129·67) |
| S-Omicron | 7·39 (5·63; 9·70) | 5·19 (3·93; 6·85) | 7·20 (4·93; 10·53) | 8·77 (6·34; 12·14)f | 44·52 (22·27; 89·00)k | 25·00 (12·46; 50·20) |
S = Spike protein; GMCs = geometric mean concentration; CI = confidence interval; S-ancestral – spike antibodies to ancestral virus; S-beta = Spike antibodies to beta variant; S-delta = Spike antibodies to delta variant.
Wave-1 maternal S-ancestral levels in those whose titres increased in wave 2 vs those whose titres declined or remained the same, p<0·001.
Wave-1 maternal S-beta levels in those whose titres increased in wave 2 vs those whose titres declined or remained the same, p<0·001.
Wave-2 maternal S-ancestral levels in those whose titres increased in wave 3 vs those whose titres declined or remained the same, p=0·011.
Wave-2 maternal S-beta levels in those whose titres increased in wave 3 vs those whose titres declined or remained the same, p=0·030.
94 mothers with Omicron results whose titres increased between wave 2 and wave 3.
58 mothers with Omicron results whose titres declined or remained the same between wave 2 and wave 3.
Wave-3 maternal S-ancestral levels in those whose titres increased in wave 4 vs those whose titres declined or remained the same, p=0·001.
Wave-3 maternal S-beta levels in those whose titres increased in wave 4 vs those whose titres declined or remained the same, p=0·002.
Wave-3 maternal S-delta levels in those whose titres increased in wave 4 vs those whose titres declined or remained the same, p<0·001.
112 mothers with Omicron results whose titres increased between wave 3 and wave 4; Wave-3 maternal S-omicron levels in those whose titres increased in wave 4 vs those whose titres declined or remained the same, p=0·004.
32 mothers with Omicron results whose titres declined or remained the same between wave 3 and wave 4; Wave-3 maternal S-omicron levels in those whose titres increased in wave 4 vs those whose titres declined or remained the same, p=0·004.