Table 2.
Neutralising antibody titres Data are n, GMT (95% CI), GMTR (95% CI), or n (%; 95% CI). GMTs, GMTRs, and seroconversion rates for SARS-CoV-2 neutralising antibodies measured by MNT50 or plaque PRNT50 with values from a phase 2 adult study
| Group 1 | Group 2 | Group 3 | Adults13 | ||
|---|---|---|---|---|---|
| MNT50 | |||||
| Day 0 | |||||
| n | 175 | 175 | 175 | NA | |
| GMT | 10·1 (8·9–11·5) | 8·5 (7·8–9·3) | 5·8 (5·7–5·9) | NA | |
| Day 28 | |||||
| n | 175 | 157 | 175 | NA | |
| GMT | 21·9 (17·8–27·1) | 31·8 (24·9–40·6) | 14·8 (13·7–16·0) | NA | |
| Seroconverted* | 44 (25%; 19·3–32·1) | 70 (45%; 37·0–52·4) | 26 (15%; 10·3–20·9) | NA | |
| Day 56 | |||||
| n | 175 | 157 | 173 | 177 | |
| GMT | 138·8 (111·0–173·6) | 137·4 (99·1–167·5) | 197·6 (176·4–221·4) | 160·1 (135·8–188·8) | |
| GMTR (group vs adults) | 0·87 (0·66–1·14) | 0·86 (0·64–1·16) | 1·23 (1·01–1·51) | 0·98 (0·80–1·19)† | |
| Seroconverted* | 158 (90%; 84·9–94·2) | 141 (90%; 84·0–94·1) | 173 (100%; 97·9–100) | 171 (97%; 92·8–98·7) | |
| p value vs adult | <0·05 | <0·05 | <0·05 | NA | |
| PRNT50 | |||||
| Day 0 | |||||
| n | 175 | 175 | 175 | NA | |
| GMT | 0·20 (0·14–0·27) | 0·11 (0·09–0·14) | 0·15 (0·12–0·18) | NA | |
| Day 28 | |||||
| n | 175 | 175 | 175 | NA | |
| GMT | 11·2 (7·0–17·9) | 13·5 (9·3–19·6) | 9·1 (6·1–13·5) | NA | |
| Seroconverted* | 111 (63%; 56·1–70·2) | 143 (82%; 75·3–86·8) | 126 (72%; 64·3–77·6) | NA | |
| Day 56 | |||||
| n | 175 | 168 | 172 | 177 | |
| GMT | 317·4 (224·4–449·2) | 366·9 (297·0–453·3) | 358·6 (287·2–447·8) | 197·0 (155·6–249·4) | |
| GMTR (group vs adults) | 1·61 (1·05–2·43) | 1·86 (1·35–2·55) | 1·82 (1·31–2·51) | 1·76 (1·32–2·33)† | |
| Seroconverted* | 166 (95%, 90·5–97·6) | 165 (98%; 94·9–99·6) | 169 (98%; 95·0–99·6) | 174 (98%; 95·1–99·6) | |
| p value vs adult | ns | ns | ns | NA | |
MNT50=microneutralisation test. NA=not applicable. GMT=geometric mean titres. GMTR=geometric mean titre ratio. PRNT50=plaque reduction neutralisation test. ns=non-significant (p value >0·1).
Seroconversion defined a four-times increase in titre over baseline at day 0. GMTR for neutralising antibodies measured by MNT or PRNT between paediatric groups 1, 2, and 3 in this study and adults in phase 2 study.14 Thus, a paediatric age subgroup was considered non-inferior to the adult group if the 95% CI for GMTR (GMT in a paediatric subgroup/GMT in adults) had a lower limit of at least 0·5. The PRNT GMTR (GMT in a paediatric subgroup/GMT in adults) had a lower limit of at least 1, indicating a superior response in children when compared with adults.
All children versus adults.