Table 3.
Global immunological results by study groups at 42 and 56 days (Phase 2).
| Group | Placebo | RBD 25 μg | RBD 50 μg | p-value* |
|---|---|---|---|---|
| Seroconversion of anti-RBD IgG % (95% CI) | ||||
| Day 42 | 8 / 239 3·3% (1·5-6·5) |
190 / 239 79·5% (73·8-84·4) |
216 / 241 89·6% (85·1-93·2) |
0·0032 |
| Day 56 | 11 / 239 4·6% (2·3-8·1) |
185 / 238 77·7% (72·0-82·9) |
214 / 240 89·2% (84·5-92·82) |
0·0012 |
| Geometric mean titers of RBD-IgG antibodies (95% CI) | ||||
| Day 42 | 2·21 (2·08-2·35) | 39·62 (31·30-50·14) | 93·46 (73·96-118·10) | <0·0001 |
| Day 56 | 2·13 (2·01-2·26) | 36·66 (27·84-43·17) | 80·36 (63·97-100·93) | <0·0001 |
| Inhibition to RBD-ACE2 binding % (95% CI) | ||||
| Day 42 | 11 / 239 4·6% (2·3-8·1) |
137 / 239 57·3% (50·8-63·7) |
176 / 241 73·0% (67·0-78·5) |
0·0004 |
| Day 56 | 13 / 239 5·4% (2·9-9·1) |
132 / 238 55·5% (48·9–61·9) |
173 / 240 72·1% (65·9-77·7) |
0·0002 |
| Inhibition to RBD-ACE2 binding Media (95% CI) | ||||
| Day 42 | 5·00 (3·64-6·36) | 41·15 (37·09-45·21) | 53·52 (49·29-57·74) | <0·0001 |
| Day 56 | 3·82 (2·68-4·96) | 36·80 (32·78-40·82) | 53·40 (49·05-57·74) | <0·0001 |
| Neutralizing antibodies against live SARS-CoV-2 (95% CI) | ||||
| Day 56 | - | 58 / 61 95·1% (86·3-99·9) |
146 / 150 97·3% (93·3-99·3) |
0·69 |
| Geometric mean of neutralizing antibody titers against live SARS-CoV-2 (95% CI) | ||||
| Day 56 | - | 24·12 (17·56-33·14) | 30·81 (25·14-33·75) | 0·19 |
RBD: receptor binding domain. ACE-2: angiotensin-converting enzyme. ±SD: plus minus standard deviation. Data is n/N (%; 95% CI) for seroconversion rates of anti-RBD IgG, proportion of individuals with inhibition to RBD-ACE2 binding and neutralizing antibodies to SARS-CoV-2. Geometric mean titers are shown with 95% CI. Inhibition to RBD-ACE-2 are shown in means ± Standard deviation and 95% CI. Days 42 and 56 refers to 14 and 28 days, respectively, after the third dose of the 0-14-28 days vaccination schedule. *p-values correspond to comparisons between 25 μg and 50 μg groups.