Table 2. Binding and Neutralizing Antibody Responses.*.
| Variable | mRNA-1273 Booster | Ad26.COV2.S Booster | BNT162b2 Booster | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Primary Ad26.COV2.S | Primary mRNA-1273 | Primary BNT162b2 | Primary Ad26.COV2.S | Primary mRNA-1273 | Primary BNT162b2 | Primary Ad26.COV2.S | Primary mRNA-1273 | Primary BNT162b2 | |
| Group no. | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| No. of participants on day 15 | 53 | 51 | 50 | 50 | 49 | 50 | 52 | 51 | 49 |
| IgG serum binding antibody titer † | |||||||||
| GMT (95% CI) | |||||||||
| Day 1 | 59 (46–76) |
872 (680–1117) |
357 (262–484) |
71 (48–106) |
639 (514–794) |
321 (251–410) |
75 (55–103) |
534 (445–642) |
224 (177–282) |
| Day 15 | 3244 (2540–4142) |
6865 (5840–8070) |
6155 (4895–7739) |
326 (236–451) |
3029 (2433–3772) |
1905 (1498–2422) |
2563 (2052–3201) |
5256 (4513–6120) |
3345 (2711–4127) |
| Day 29 | 2986 (2478–3598) |
6224 (5282–7333) |
5231 (4274–6402) |
369 (291–467) |
4560 (3544–5867) |
2600 (2086–3240) |
2277 (1833–2828) |
5273 (4567–6088) |
3164 (2649–3779) |
| Percent with ≥2 factor increase from baseline titer on day 15 (95% CI) | 100 (93–100) |
96 (86–100) |
98 (89–100) |
86 (73–94) |
84 (70–93) |
92 (81–98) |
98 (90–100) |
100 (93–100) |
100 (93–100) |
| Increase in GMT from baseline (95% CI) | 55 (40–75) |
8 (6–10) |
17 (13–22) |
5 (4–6) |
5 (4–6) |
6 (5–8) |
34 (26–45) |
10 (8–12) |
15 (12–19) |
| Pseudovirus neutralizing antibody ‡ | |||||||||
| GMT (95% CI) | |||||||||
| Day 1 | 9 (6–13) |
89 (68–116) |
25 (18–34) |
8 (5–12) |
62 (45–85) |
19 (13–26) |
9 (6–14) |
58 (45–74) |
21 (15–30) |
| Day 15 | 676 (518–883) |
902 (728–1118) |
786 (596–1035) |
31 (22–44) |
382 (290–503) |
216 (158–297) |
344 (244–484) |
694 (578–832) |
437 (334–573) |
| Day 29 | 432 (323–578) |
700 (569–862) |
496 (370–663) |
30 (22–40) |
528 (383–729) |
267 (196–362) |
242 (190–309) |
515 (436–609) |
306 (244–384) |
| Percent with ≥4 factor increase from baseline titer on day 15 (95% CI) | 100 (93–100) |
84 (71–93) |
100 (93–100) |
50 (36–64) |
61 (46–75) |
82 (69–91) |
98 (90–100) |
94 (84–99) |
98 (89–100) |
| Increase in GMT from baseline (95% CI) | 73 (52–101) |
10 (8–13) |
32 (24–42) |
4 (3–6) |
6 (4–9) |
12 (9–18) |
36 (25–53) |
12 (9–15) |
20 (15–27) |
*
The confidence intervals (CI) have not been adjusted for multiplicity, so the intervals should not be used to infer definitive treatment effects for secondary outcomes.
†
The IgG serum binding antibody response was measured as the geometric mean titer (GMT) of the binding antibody units per milliliter against the wild-type SARS-CoV-2 variant (WA1 S-2P).
‡
The pseudovirus neutralizing antibody response was measured with the use of a pseudovirus expressing the D614G mutation of the SARS-CoV-2 spike protein and reported as the titer in international units of the 50% inhibitory dose (IU50) per milliliter.