Geometric mean titres of neutralising, anti-receptor-binding domain, and anti-spike glycoprotein antibodies at different time points in phase I
| Antibody | Stage I (18–50 years) | Stage II (51–75 years) | |||
| Geometric mean titre* (95% CI) | Geometric mean titre (95% CI) | ||||
| 3 µg | 5 µg | Placebo | 5 µg | Placebo | |
| Neutralising antibody | |||||
| Day 0 | 1.76 (1.37 to 2.26) | 1.36 (0.87 to 2.11) | 1.55 (1.20 to 2.01) | 0.37 (0.28 to 0.48) | 0.56 (0.41 to 0.76) |
| Day 14 | 2.46 (1.26 to 4.79) | 2.76 (1.58 to 4.81) | 2.36 (0.70 to 8.00) | 0.92 (0.42 to 2.02) | 0.31 (0.20 to 0.49) |
| Day 21 | 6.26 (3.08 to 12.71) | 7.79 (3.61 to 16.80) | 1.31 (1.08 to 1.60) | 5.39 (2.69 to 10.83) | 0.80 (0.46 to 1.40) |
| Day 28 | 7.89 (3.60 to 17.28) | 15.38 (8.02 to 29.48) | 2.76 (0.63 to 12.11) | 12.52 (7.29 to 21.51) | 0.85 (0.27 to 2.66) |
| Anti-receptor binding domain IgG | |||||
| Day 0 | 0.19 (0.10 to 0.37) | 0.17 (0.10 to 0.29) | 0.1 (0.1 to 0.1) | 0.14 (0.10 to 0.21) | 0.1 (0.1 to 0.1) |
| Day 14 | 0.37 (0.16 to 0.84) | 2.24 (1.27 to 3.95) | 0.1 (0.1 to 0.1) | 0.30 (0.14 to 0.66) | 0.1 (0.1 to 0.1) |
| Day 21 | 0.86 (0.38 to 1.95) | 7.63 (5.18 to 11.22) | 0.14 (0.08 to 0.28) | 4.00 (1.84 to 8.71) | 0.1 (0.1 to 0.1) |
| Day 28 | 1.23 (0.56 to 2.69) | 7.58 (5.66 to 10.14) | 0.12 (0.09 to 0.16) | 6.02 (3.26 to 11.13) | 0.1 (0.1 to 0.1) |
| Anti-spike glycoprotein IgG | |||||
| Day 0 | 0.85 (0.30 to 2.40) | 0.26 (0.12 to 0.56) | 0.11 (0.09 to 0.13) | 0.33 (0.14 to 0.75) | 0.27 (0.11 to 0.67) |
| Day 14 | 2.26 (0.67 to 7.58) | 2.28 (0.89 to 5.84) | 0.19 (0.08 to 0.46) | 0.69 (0.24 to 1.98) | 0.19 (0.10 to 0.34) |
| Day 21 | 10.19 (4.45 to 23.34) | 54.84 (36.32 to 82.82) | 0.68 (0.30 to 1.54) | 19.56 (7.64 to 50.09) | 0.17 (0.09 to 0.31) |
| Day 28 | 10.39 (4.17 to 25.88) | 70.41 (55.01 to 90.13) | 0.30 (0.13 to 0.73) | 53.69 (29.09 to 99.10) | 0.18 (0.09 to 0.40) |
Results reported at baseline (day 0), 2 weeks after the first vaccination (day 14), and 2 weeks after the second vaccination (day 28) for 3 µg, 5µg, 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 the second injection and thus was excluded from data analysis.
*Neutralising antibody is reported in µg/mL—anti-receptor binding domain IgG in RU/mL—and anti-spike glycoprotein IgG in RU/mL.
RT-PCR, reverse transcription PCR.