The proportion of patients with seroconversion for neutralising, anti-receptor-binding domain, and anti-spike glycoprotein antibodies in phase I
| Antibody | Stage I (18–50 years) | Stage II (51–75 years) | |||
| Seroconversion rate* (95% CI) | Seroconversion rate (95% CI) | ||||
| 3 µg | 5 µg | Placebo | 5 µg | Placebo | |
| Neutralising antibody | |||||
| Day 14 | 12.50 (2.66 to 32.36) | 25.00 (9.77 to 46.71) | 12.50 (0.32 to 52.65) | 22.73 (7.82 to 45.37) | 0 (0 to 0) |
| Day 21 | 33.33 (15.63 to 55.32) | 58.33 (36.64 to 77.89) | 0 (0 to 0) | 77.27 (54.63 to 92.18) | 12.50 (0.32 to 52.65) |
| Day 28 | 45.83 (25.55 to 67.18) | 70.83 (48.91 to 87.38) | 37.5 (8.52 to 75.51) | 100 (84.56 to 100) | 12.50 (0.32 to 52.65) |
| Anti-receptor binding domain IgG | |||||
| Day 14 | 16.67 (4.74 to 37.38) | 75.00 (53.29 to 90.23) | 0 (0 to 0) | 22.73 (7.82 to 45.37) | 0 (0 to 0) |
| Day 21 | 16.67 (4.74 to 37.38) | 87.50 (67.64 to 97.34) | 12.50 (0.32 to 52.65) | 77.27 (54.63 to 92.18) | 0 (0 to 0) |
| Day 28 | 54.17 (32.82 to 74.45) | 87.50 (67.64 to 97.34) | 0 (0 to 0) | 86.36 (65.09 to 97.09) | 0 (0 to 0) |
| Anti-spike glycoprotein IgG | |||||
| Day 14 | 25.00 (9.77 to 46.71) | 66.67 (44.68 to 84.37) | 12.50 (0.32 to 52.65) | 18.18 (5.19 to 40.28) | 0 (0 to 0) |
| Day 21 | 70.83 (48.91 to 87.38) | 91.67 (73.00 to 98.97) | 75.00 (34.91 to 96.81) | 72.73 (49.78 to 89.27) | 0 (0 to 0) |
| Day 28 | 70.83 (48.91 to 87.38) | 91.67 (73.00 to 98.97) | 50.00 (15.7 to 84.3) | 86.36 (65.09 to 97.09) | 12.50 (0.32 to 52.65) |
Results reported as the proportion of participants with at least fourfold higher seroconversion than the baseline titre at 2 weeks after the first vaccination (day 14), 3 weeks after the first vaccination (day 21), and 2 weeks after the second vaccination (day 28) for 3 µg, 5 µg, and placebo groups. In stage I, one participant in the 3 µg group became RT-PCR positive for COVID-19 on day seventh after the first dose and was thus excluded from the study. In stage II, one participant in the 5 µg group was excluded from the study and did not receive any doses due to white coat syndrome. Another participant in the 5 µg group of stage II became RT-PCR positive for COVID-19 within a day after second injection and thus was excluded from data analysis.
**Defined as a postvaccination titre that was at least four-fold higher than the baseline titre.
RT-PCR, reverse transcription PCR.