elevated levels of anti-sars-cov2 igg antibody in health care workers in hospitals from hamadan province, iran: a prospective study

Aim: seroprevalence among health care workers (hcws) has been estimated in different studies in various regions and countries. this study aimed to screen the immunoglobulin m (igm) and igg seroprevalences and to assess the durability of igg seropositivity, as well as the incidence of subsequent severe acute respiratory syndrome coronavirus 2 (sars-cov-2) infection in a group of iranian hcws. methods: this voluntary serological screening was prospectively performed on 800 hcws (492 females and 308 males) in hamadan between november 2020 and february 2021. anti-sars-cov-2 igg and igm antibodies were assessed by the enzyme-linked immunosorbent assay method at two-time intervals. results: overall, 243 out of 800 (30.38%) and 66 (8.25%) cases were igg and igm seropositive at their first antibody assessment, respectively. the male staff had a higher seroprevalence than females (31.49% vs. 29.67% for igg, p = 0.59 and 10.39% vs. 6.91% for igm, p = 0.08). higher prevalences for both antibodies were found in the age group of 30-39.9 years (p = 0.12 and p = 0.05, respectively). in the second antibody screening, 81 (56.6%) cases were igg seropositive. the mean titer of the first igg antibody assessment in seropositive cases was lower than that of the second titer (2.95 ± 2.07 vs. 5.08 ± 4.01 cut-off index (coi) , p = 1.4×10-5). moreover, the comparison of the first and second igg titers among 81 seropositive cases demonstrated a significantly increased level of anti-sars-cov-2 antibody (5.08 ± 4.01 vs. 3.49 ± 2.41 coi, p = 0.002). conclusions: our findings revealed that the mean level of the anti-sars-cov-2 igg antibody was significantly increased in the seropositive individuals after 2 months of follow-up.