COVID-19 Immune Status in the General Population in Kirkuk Province, Iraq

Background: Seroepidemiologic studies provided data that support the gold standard diagnosis approaches for COVID-19, such as viral isolation and antigen detection in body fluids or human tissue. Aim: To estimate the seroprevalence of IgM and IgG to COVID-19 in the general population in Kirkuk Province as an example of the Iraqi population and clarify the influence of sex and age on IgM and IgG seroprevalence. Materials and Methods: A retrospective and prospective study was conducted to determine the immune response to SARS-CoV-2 infection during the period from 23 July 2020 to the end of December 2021. The information was gathered from healthcare center records for a retrospective study, while the prospective study included 385 patients and blood collected from them for IgM and IgG antibody determination. Results: The overall SARS-CoV-2 IgM seroprevalence was 22.3%, with a range of 3.6% to 31.6% and a significant difference between health care centers. While the overall SARS-CoV-2 IgG seroprevalence was 36.2%, with a range of 25.4% to 56.5%, there was a significant difference in seroprevalence between centers. SARS-CoV-2 IgM seroprevalence with no significant difference between males and females, while SARS-CoV-2 IgG seroprevalence was significantly lower in males than in females. Both IgM and IgG seroprevalence are significantly different among age groups. The prospective study shows that SARS-CoV-2 IgM seroprevalence was 7.5%, while 78.2% for IgG and with no significant differences in relation to sex and age groups. The present study findings indicated that the SARS-CoV-2 IgG seroprevalence rate increased with time as an outcome of infection or vaccination program. Conclusion: SARS-CoV-2 IgG seroprevalence increased with time, and herd immunity in the Kirkuk community was 36.2% for the years 2020/2021 and increased to reach 78.2%, and this rate was within the accepted level of herd immunity. A large-scale national seroepidemiologic study was warranted.