Table 1.
Humoral immunogenicity outcomes against wild type SARS-CoV-2 post-dose 2 and post-dose 3 of CoronaVac in the evaluable analysis population
| Variables | Intramuscular | Intradermal | ||
|---|---|---|---|---|
| 2 doses | 3 doses | 2 doses | 3 doses | |
| S IgG on ELISA | ||||
| n | 116 | 56 | 47 | 36 |
| GM OD450 value (95% CI) | 0.536 (0.493–0.582) | 0.930 (0.830–1.040) | 0.634 (0.562–0.716) | 1.050 (0.983–1.120) |
| %positive (≥ LOD at 0.3) | 94.0 | 98.2 | 95.7, P > 0.9999 | 100.0, P > 0.9999 |
| S-RBD IgG on ELISA | ||||
| n | 119 | 60 | 54 | 42 |
| GM OD450 value (95% CI) | 1.200 (1.100–1.310) | 1.770 (1.680–1.870) | 2.160 (2.040–2.290) | 2.450 (2.330–2.570) |
| %positive (≥ LOD at 0.5) | 96.6 | 100.0 | 100.0, P = 0.311 | 100.0, P > 0.9999 |
| S-RBD ACE2-blocking antibody on sVNT | ||||
| n | 119 | 60 | 54 | 42 |
| GM% inhibition (95% CI) | 71.2 (66.7–76.0) | 84.9 (81.3–88.6) | 78.4 (74.6–82.5) | 91.3 (88.3–94.4) |
| %positive (≥ LOQ at 30%) | 96.6 | 100.0 | 100.0, P = 0.311 | 100.0, P > 0.9999 |
| Neutralising antibody on PRNT | ||||
| n | 119 | 60 | 54 | 42 |
| GM PRNT90 (95% CI) | 9.83 (8.67–11.10) | 17.80 (13.70–23.30) | 10.70 (8.09–14.10) | 38.70 (27.60–54.20) |
| %positive (≥ LOD at 10) | 65.6 | 78.3 | 61.1, P = 0.610 | 97.6, P = 0.007 |
| GM PRNT50 (95% CI) | 26.80 (23.00–31.10) | 55.30 (43.20–70.70) | 30.20 (23.50–38.80) | 110.00 (82.50–145.00) |
| %positive (≥ LOD at 10) | 96.6 | 100.0 | 98.2, P > 0.9999 | 100.0, P > 0.9999 |
| S IgG avidity on ELISA | ||||
| n | 109 | 55 | 45 | 36 |
| GM avidity index (95% CI) | 20.50 (19.10–22.10) | 38.50 (34.60–42.80) | 6.95 (5.03–9.60) | 53.30 (48.30–58.80) |
| S IgG FcγRIIIa-binding on ELISA | ||||
| n | 116 | 56 | 47 | 36 |
| GM OD450 value (95% CI) | 0.749 (0.649–0.864) | 1.410 (1.210–1.630) | 1.100 (0.955–1.270) | 1.790 (1.710–1.880) |
| %positive (≥ LOD at 0.28) | 87.1 | 98.2 | 95.7, P = 0.156 | 100.0, P > 0.9999 |
SARS-CoV-2 severe acute respiratory syndrome coronavirus 2, S spike protein, N nucleocapsid protein, IgG immunoglobulin G, ELISA enzyme-linked immunosorbent assay, GM geometric mean, OD optical density, CI confidence interval, LOD limit of detection, LOQ limit of quantification, RBD receptor-binding domain, ACE-2 angiotensin-converting enzyme-2, sVNT surrogate virus neutralisation test, PRNT plaque reduction neutralisation titre, PRNT90 90% plaque reduction neutralisation titre, PRNT50 50% plaque reduction neutralisation titre, FcγRIIIa Fc gamma receptor III-a. P values compare the proportion of positive responses between intramuscular and intradermal administration by Fisher’s exact test