Table 2.
SARS-CoV-2 IgG titres against the spike glycoprotein, receptor-binding domain, and nucleocapsid protein
|
Geometric mean titre (95% CI) |
Seroconversion rate*(95% CI) |
|||
|---|---|---|---|---|
| 3 μg with Algel-IMDG | 6 μg with Algel-IMDG | 3 μg with Algel-IMDG | 6 μg with Algel-IMDG | |
| Anti-spike glycoprotein IgG | ||||
| Day 0 | 500·0 (500·0–500·0) | 500·0 (500·0–500·0) | .. | .. |
| Day 28 | 2574·2 (2228·9–2973·1) | 2240·5 (1942·4–2584·5) | 71·2% (64·1–77·6) | 65·0% (57·5–72·0) |
| Day 42 | 11528·8 (10 002·7–13 287·8) | 10040·0 (8667·0–11 630·5) | 98·4% (95·3–99·7) | 98·3% (95·1–99·7) |
| Day 56 | 10413·9 (9142·4–11 862·2) | 9541·6 (8245·9–11 041·0) | 98·4% (95·3–99·7) | 96·6% (92·8–98·8) |
| Anti-receptor binding domain IgG | ||||
| Day 0 | 500·0 (500·0–500·0) | 500·0 (500·0–500·0) | .. | .. |
| Day 28 | 1962·7 (1726·2–2231·6) | 2031·6 (1777·3–2322·3) | 58·7% (51·2–65·9) | 58·2% (50·6–65·6) |
| Day 42 | 5572·3 (4897·5, 6339·9) | 4980·8 (4366·7, 5681·3) | 94·0% (89·6, 97·0) | 93·2% (88·5, 96·5) |
| Day 56 | 5874·0 (5194·8, 6642·0) | 5558·0 (4859·9, 6356·5) | 96·2% (92·3, 98·5) | 94·4% (89·9, 97·3) |
| Anti-nucleocapsid protein IgG | ||||
| Day 0 | 500·0 (500·0–500·0) | 500·0 (500·0–500·0) | .. | .. |
| Day 28 | 2734·1 (2375·1–3147·5) | 2490·4 (2161·7–2869·2) | 72·3% (65·2–78·6) | 71·2% (63·9–77·7) |
| Day 42 | 8957·2 (7778·6–10314·3) | 9211·2 (7939·3–10 686·8) | 97·3% (93·8–99·1) | 95·5% (91·3–98·0) |
| Day 56 | 8626·0 (7528·6–9883·4) | 8754·0 (7589·4–10 097·4) | 97·3% (95·3–100·0) | 96·6% (92·8–98·8) |
ELISA results at baseline (day 0), 4 weeks after the first vaccination (day 28), 2 weeks after the second vaccination (day 42), and 4 weeks after the second vaccination (day 56) for the 3 μg with Algel-IMDG and the 6 μg with Algel-IMDG groups are shown. The number of participants in the 3 μg with Algel-IMDG group included in the immunogenicity analysis was 190 on day 0, 189 on day 28, 187 on day 42, and 184 on day 56. The number of participants in the 6 μg with Algel-IMDG group included in the immunogenicity analysis was 190 on day 0, 187 on day 28, 179 on day 42, and 177 on day 56. The cutoff for detectable antibodies was 1/500. Endpoint titre dilution for days 28, 42, and 56 sera samples were established with baseline (day 0) and interpolated from the raw optical density data of the corresponding day 0 sample. The cutoff (mean ±3 SD) for day 0 was calculated considering the absorbance of all sera dilutions (1/500 to 1/32 000) tested, except the lowest dilution (1/500).
Defined as a post-vaccination IgG titre that was at least four-fold higher than the baseline titre.