Table 4. Seroprevalence of IgG antibodies against SARS-CoV-2 in the general population by vaccination status, June–July 2021.
| Characteristic | Unvaccinated | Vaccinated with 1 dose | Vaccinated with 2 doses | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Number tested | Number positive (anti-N and/or anti-S1-RBD antibodies) | Cluster- and test-adjusted seroprevalence, percent (95% CI) | Number tested | Number positive (anti-N and/or anti-S1-RBD antibodies) | Cluster- and test-adjusted seroprevalence, percent (95% CI) | Number tested | Number positive (anti-N and/or anti-S1-RBD antibodies) | Cluster- and test-adjusted seroprevalence, percent (95% CI) | |
| Age | |||||||||
| 18–44 years | 8,986 | 5,381 | 60.8 (59.2–62.3) | 2,426 | 1,896 | 80.4 (78.2–82.4) | 1,096 | 958 | 89.1 (86.7–91.3) |
| 45–60 years | 2,701 | 1,778 | 67.0 (64.8–69.1) | 1,830 | 1,521 | 85.5 (83.4–87.3) | 1,013 | 917 | 91.9 (89.7–93.6) |
| >60 years | 912 | 599 | 67.0 (63.6–70.4) | 782 | 599 | 78.9 (75.4–82.0) | 522 | 456 | 88.7 (85.4–91.5) |
| Gender | |||||||||
| Male | 10,040 | 5,962 | 59.6 (57.8–61.4) | 2,598 | 2,050 | 81.0 (79.0–82.9) | 1,136 | 999 | 89.4 (87.1–91.5) |
| Female | 11,223 | 6,998 | 64.9 (63.2–66.4) | 2,436 | 1,962 | 83.1 (81.1–84.9) | 1,493 | 1,330 | 90.7 (88.6–92.3) |
| Other | 26 | 17 | 74.0 (44.9–90.8) | 4 | 4 | — | 2 | 2 | — |
| Area of residence | |||||||||
| Rural | 3,702 | 2,280 | 62.1 (60.5–63.7) | 1,046 | 846 | 81.1 (79.2–82.9) | 515 | 459 | 90.1 (88.0–91.7) |
| Urban non-slum | 16,236 | 9,832 | 63.6 (60.2–66.8) | 3,603 | 2,840 | 83.2 (79.8–86.1) | 1,941 | 1,716 | 90.4 (86.9–93.0) |
| Urban slum | 1,351 | 865 | 64.6 (59.0–69.8) | 389 | 330 | 87.1 (82.1–90.9) | 175 | 156 | 90.9 (84.7–94.7) |
| Previous COVID-19 test result | |||||||||
| Reported positive for COVID-19 | 487 | 402 | 86.0 (82.2–89.1) | 145 | 134 | 94.7 (90.1–97.2) | 150 | 138 | 93.8 (88.6–96.7) |
| Reported negative for COVID-19 | 1,732 | 1,051 | 62.9 (59.7–66.1) | 962 | 739 | 80.1 (76.9–83.0) | 724 | 634 | 89.4 (86.5–91.8) |
| Don’t know | 119 | 58 | 60.2 (46.5–72.5) | 36 | 28 | 84.1 (67.5–93.1) | 16 | 11 | 66.7 (37.4–87.0) |
| Vaccine type | |||||||||
| Covaxin | — | — | — | 385 | 302 | 80.8 (75.7–85.0) | 202 | 171 | 86.3 (80.4–90.8) |
| Covishield | — | — | — | 4,565 | 3,636 | 82.0 (80.3–83.6) | 2,380 | 2,115 | 90.3 (88.5–91.8) |
| Individuals with optimal interval between vaccination and blood sample collection (21 days or more after first dose, 7 days or more after second dose) | |||||||||
| Covaxin | — | — | — | 223 | 186 | 84.3 (78.4–88.9) | 201 | 170 | 86.3 (80.3–90.7) |
| Covishield | — | — | — | 3,045 | 2,535 | 84.8 (83.1–86.5) | 2,380 | 2,115 | 90.3 (88.5–91.8) |
N, nucleocapsid protein.