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.