Seroepidemiology of COVID-19 in High-Risk Occupational Groups in West of Iran, November 2020

Background and purpose: The actual prevalence of Coronavirus Disease 2019 (COVID-19) can only be estimated by population-based serological examinations and individuals without clinical symptoms may not be identified or reported. In this sero-epidemiological study we aimed at exploring the serum prevalence of COVID-19 in highly exposed occupational groups in western Iran. Materials and methods: A total of 1106 people with jobs with a high potential for exposure to COVID-19 (excluding doctors) were selected in Sanandaj, Kermanshah, and Hamedan. Demographic information of all participants were recorded and venous blood samples (3 ml) were taken. IgG levels were measured to determine the serum prevalence of immunoglobulin using EUROIMMUN kit. Results: Until 15 November 2020, IgG antibody was detected positive in 317 people (28.7%). In Sanandaj, Hamedan, and Kermanshah there were 132 (32%), 88 (26%), and 99 (27.3%) people with IgG-positive antibodies, respectively. There were no significant differences in rates of positive COVID-19 IgG antibody between the cities (P= 0.158). Among individuals with IgG antibody positive (n=317), 35.4% were asymptomatic and only 3.2% were admitted to hospital because of COVID-19. Conclusion: High prevalence of COVID-19 antibodies in people with working activities of high potential for exposure to known or suspected sources of SARS-CoV-2 and a high number of asymptomatic individuals in this group showed that appropriate personal equipment and adhering to strict rules play a critical role in limiting the disease transmission.