Table 1.
Seropositivity of the participants against SARS-CoV-2a.
| August 2020 (n = 724) |
February 2021 (n = 866) |
June 2021 (n = 436) |
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|---|---|---|---|---|---|---|
| Parameterb | Positive result [n (%)] | Adjusted Positivityc[% (95% CI)] | Positive result [n (%)] | Adjusted Positivityc[% (95% CI)] | Positive result [n (%)] | Adjusted Positivityc[% (95% CI)] |
| IgG-N | 77 (10.63%) | 10.61% (8.37–12.85) | 349 (40.3%) | 40.21% (36.95–43.48) | 202 (46.33%) | 46.23% (41.55–50.91) |
| IgG-S | 64 (8.83%) | – | 146 (16.85%) | – | 69 (15.82%) | – |
| IgM-S | 7 (1%) | – | 31 (3.49%) | – | 16 (3.66%) | – |
| Neutralizing antibodyd | 70 (90.91%) | 90.91% (97.33–84.49) | 182 (52.14%) | 52.14% (57.39–46.91) | 140 (69.30%) | 69.30% (75.67–62.95) |
a
Assessments were done at three different time points, namely August 2020, February 2021, and June 2021.
b
IgG-N: anti-N protein IgG; IgG-S: anti-S protein IgG; IgM-S: anti-S protein IgM; Neutralizing antibody: neutralizing antibody against SARS-CoV-2.
c
Adjusted positivity was calculated considering 99.8% sensitivity and 100% specificity for the IgG-N kit (Roche) and 100% sensitivity and 100% specificity for the neutralizing antibody kit (Genscript). Kits used for IgG-S and IgM-S were ICMR-approved, but, there were no information about the sensitivity and specificity.
d
Only samples that were seropositive for IgG-N, IgG-S and/or IgM-S were considered for the neutralizing antibody assay.