Table 3.
Evolution of anti-RBD antibody titers in study participants.
| Estimated Anti-RBD Antibody Titers (AU/mL), GMT (95% CI) | ||||||||
|---|---|---|---|---|---|---|---|---|
| Months from 2nd Dose of the BNT162b2 Vaccine a | ||||||||
| 1.5 | 3 | 7 | 9 | 13 | 16 | 19 | 26 | |
| All participants | 5384 (4556–6363) |
4432 (3785–5165) |
1325 * (1169–1503) |
1305 (1151–1479) |
13,966 * (11,962–16,906) |
20,601 * (18,039–23,528) |
20,214 (17,451–23,415) |
17,040 (13,938–20,832) |
| Age | ||||||||
| <47 years | 5869 (4811–7161) |
4764 (3938–5764) |
1473 * (1245–1742) |
1223 (1019–1467) |
12,581 * (10,371–15,262) |
18,639 (15,457–22,476) |
18,997 (15,558–23,195) |
17,128 (13,328–22,013) |
| ≥47 years | 4931 (4023–6044) |
4098 (3375–4975) |
1153 * (973–1367) |
857 (717–1026) |
15,532 * (12,703–18,992) |
22,812 (18,978–27,420) |
21,534 (17,851–25,977) |
16,950 (13,275–21,643) |
| Gender | ||||||||
| Male | 5659 (4534–7064) |
4734 (3817–5873) |
1485 * (1221–1805) |
1228 (998–1511) |
16,068 * (12,767–20,223) |
26,695 (21,539–33,086) |
22,564 (18,183–28,000) |
20,656 (15,671–27,229) |
| Female | 5232 (4334–6314) |
4250 (3558–5077) |
1211 * (1040–1410) |
924 (784–1089) |
12,880 * (10,783–15,385) |
17,740 (15,026–20,945) |
18,972 (15,865–22,687) |
15,249 (12,126–19,177) |
| Previous SARS-CoV-2 infection b | ||||||||
| No | 4570 (3828–5455) |
3632 (3076–4289) |
1076 (937–1236) |
853 (734–991) |
14,691 (12,411–17,389) |
22,600 (19,526–26,158) |
22,421 (19,188–26,200) |
19,907 ** (16,105–24,608) |
| Yes |
10,658 ** (8010–14,181) |
10,028 ** (7587–13,254) |
2909 ** (2230–3795) |
2210 ** (1664–2933) |
11,312 (8382–15,265) |
14,009 (10,321–19,014) |
13,128 (9447–18,244) |
8916 (6205–12,810) |
| SARS-CoV-2 infections during the study c | ||||||||
| No | 5562 (4136–7478) |
4528 (3362–6100) |
1080 (815–1431) |
808 (596–1097) |
11,851 (8308–16,903) |
14,001 (9247–21,199) |
10,008 (6750–14,839) |
8814 (5370–14,466) |
| Yes | 5354 (4493–6380) |
4403 (3737–5188) |
1348 (1177–1543) |
1068 (922–1237) |
14,365 (12,217–16,891) |
22,013 (19,539–26,619) |
22,806 ** (19,539–26,619) |
19,081 (15,445–23,573) |
Abbreviations: Anti-RBD: antibodies against the receptor-binding domain of the S1 subunit of the spike protein of SARS-CoV-2; AU/mL: arbitrary units per milliliter; GMT, geometric mean titer; 95% CI: 95% confidence interval. a All participants received two doses of BNT162b2. A booster dose of mRNA-1273 was administered to 248 (93%) study participants immediately after the 9-month time point; the bivalent Omicron-adapted BNT162b2 vaccine was administered to 93 (35%) study participants between the 19-month and the 26-month time points. b Fifty (17%) participants had documented SARS-CoV-2 infections either before the first dose of BNT162b2 (n = 37) or prior to the 1.5-month time point (n = 13). c SARS-CoV-2 infections occurring before the first dose of BNT162b2, prior to the 1.5-month time point, or during follow-up; 53 (20%) subjects who were naïve at the 1.5-month time point remained uninfected throughout the entire study. * Significant difference (p < 0.05) compared with the previous time point. ** Significant difference (p < 0.05) among groups at indicated time points.