Table 3. Geometric mean and median spike binding antibody titers of participants in study of SARS-CoV-2 spike antibody levels, by SARS-CoV-2 NAAT status and phase of predominant circulating viral strain, Dominican Republic, March 2021–August 2022*.
| Phase† | SARS-COV-2 NAAT result | No. (%) participants | GMT, BAU/mL (95% CI) | Fold difference in GMT‡ | Median titer, BAU/mL (Q1–Q3) | Fold difference in median titer |
|---|---|---|---|---|---|---|
| Pre-Delta |
Negative | 495 (76.6) | 14.1 (10.9–18.2) |
3.4
|
13.3 (0.8–132.8) | 5.5 |
| Positive |
151 (23.4) |
4.1 (2.6–6.5) |
2.4 (0.4–24.4) |
|||
| Delta |
Negative | 553 (72.4) | 604.8 (475.3–769.7) |
3.9
|
792.3 (127.8–4,805) | 4.5 |
| Positive |
211 (27.6) |
154.7 (97.8–244.7) |
176.2 (24.7–1,638.5) |
|||
| Omicron BA.1 |
Negative | 403 (86.9) | 1,288.3 (965.4–1,719.2) |
1.8
|
2,822 (511.1–8,656) | 3.4 |
| Positive |
61 (13.1) |
713.8 (375.1–1,358.5) |
837.2 (126.8–5,739) |
|||
| Omicron BA.2/4/5 |
Negative | 332 (77.9) | 1,541.4 (1,183.4–2,007.6) |
2.0
|
3,202 (1,011–6,173) | 1.7 |
| Positive |
94 (22.1) |
759.6 (468.1–1,232.6) |
1,835 (197.7–3,882.2) |
|||
| Total | Negative | 1,783 (77.5) | 300.6 (256.5–352.4) | 3.5 | 725 (31.6–4,351.5) | 6.0 |
| Positive | 517 (22.5) | 85.8 (62.9–117.1) | 121.2 (4.6–1,905) |
*N = 2,300. BAU, binding antibody units; GMT, geometric mean titer; NAAT, nucleic acid amplification test. †Phases based on dominant circulating strain: March 22–August 15, 2021 (pre-Delta, primarily Mu, Gamma, Iota, and Lambda strains), August 16–December 23, 2021 (Delta), December 24, 2021–April 30, 2022 (Omicron, BA.1), and May 1–August 17, 2022 (Omicron, BA.2, BA.4, BA.5). Appendix Figure 5 shows sequence-confirmed variant by week. ‡Fold difference is GMT or median titer of NAAT-negative participants divided by the titer of NAAT-positive participants. Bolded type indicates statistical significant result (p<0.001, by t test for GMT difference between NAAT-negative and positive-study participants).