Geometric mean titres, geometric mean ratios, and seroconversion rates of neutralising, anti-receptor-binding domain, and anti-spike glycoprotein antibodies at different time points in phase II
| Antibody | Geometric mean titre† (95% CI) | Geometric mean ratio (95% CI) | Seroconversion rate* (%) (95% CI) | ||
| 5 µg | Placebo | 5 µg | 5 µg | Placebo | |
| Neutralising antibody | |||||
| Day 0 | 0.27 (0.23 to 0.33) | 0.39 (0.26 to 0.58) | 0.69 (0.46 to 1.04) | N/A | N/A |
| Day 28 | 1.27 (0.94 to 1.73) | 0.37 (0.23 to 0.59) | 3.42 (1.80 to 6.50) | 50.24 (42.26 to 56.21) | 12.73 (5.27 to 24.48) |
| Day 42 | 11.44 (8.72 to 15.01) | 0.67 (0.36 to 1.25) | 17.05 (9.21 to 31.57) | 82.78 (76.96 to 87.63) | 25.45 (14.67 to 39.00) |
| Anti-receptor binding domain IgG | |||||
| Day 0 | 0.22 (0.19 to 0.25) | 0.22 (0.16 to 0.32) | 0.98 (0.70 to 1.39) | N/A | N/A |
| Day 28 | 0.96 (0.75 to 1.23) | 0.29 (0.18 to 0.46) | 3.31 (1.93 to 5.66) | 51.20 (44.21 to 58.15) | 20.00 (10.43 to 32.97) |
| Day 42 | 2.87 (2.39 to 3.46) | 0.41 (0.25 to 0.68) | 6.94 (4.49 to 10.74) | 77.03 (70.73 to 82.55) | 29.09 (17.63 to 42.90) |
| Anti-spike glycoprotein IgG | |||||
| Day 0 | 0.57 (0.42 to 0.77) | 0.48 (0.26 to 0.88) | 1.20 (0.62 to 2.31) | N/A | N/A |
| Day 28 | 8.78 (6.37 to 12.11) | 0.99 (0.50 to 1.97) | 8.87 (4.34 to 18.13) | 68.42 (61.65 to 74.66) | 23.64 (13.23 to 37.02) |
| Day 42 | 37.80 (29.61 to 48.25) | 3.83 (1.74 to 8.43) | 9.88 (5.32 to 18.36) | 79.90 (73.82 to 85.12) | 45.45 (31.97 to 59.45) |
Results reported at baseline (day 0), 4 weeks after the first vaccination (day 28), and 2 weeks after the second vaccination (day 42) for 5 µg and placebo groups. In phase II, 11 participants in the 5 µg group were excluded from the study due to positive RT-PCR for COVID-19 after first injection (N=9), death due to suicide via cyanide toxicity (N=1) and coadministration of another COVID-19 vaccine platform without prior notice (N=1).
*Defined as a postvaccination titre that was at least four-fold higher than the baseline titre.
†Geometeric mean titres for neutralising antibody is reported in µg/mL—anti-receptor binding domain IgG in RU/mL—and anti-spike glycoprotein IgG in RU/mL.
NA, not applicable; RT-PCR, reverse transcription PCR.