Maryam Aghajarinezhad, Yahya Salimi, Shahab Rezaeian, Ghobad Moradi, Fatemeh Khosravi Shadmani, Roya Safari Faramani, Ebrahim Shakiba, Yahya Pasdar, Behrooz Hamzeh, Nayebali Rezvani, Mitra Darbandi, Farid Najafi,
Volume 18, Issue 2 (Vol.18, No.2, Summer 2022 2022)
Abstract
Background and Objectives: Serological studies are based on the detection of antibodies. However, the produced antibodies decrease over time; therefore, such methods cannot provide a valid estimate of prevalence and incidence. The present study aimed to determine the serum prevalence and cumulative incidence in the Ravansar cohort population (Youth and RaNCD Cohort) in October 2020.
Methods: A random sample of 716 people aged > 18 years old were selected from the participants in the Ravansar cohort study in October 2020. Euroimmun anti-SARS COV-2 IgG ELISA kits (Lübeck, Germany) were used to measure antibody levels. Seroprevalence was estimated with considering of cut-off = 1, and cumulative incidence (modified and modified based on test specificity) was determined using modeling.
Results: In the present study, the serum prevalence of COVID-19 viral infection in the Ravansar cohort population from 22 October 2020 to 18 November 2020 was estimated to be %35.16 (95%CI: %31.64, %38.79). Modified Cumulative incidence and modified based on test characteristics from 20 February to 18 November 2020 were estimated to be %68.85 and %67.71, respectively.
Conclusion: Although very high cumulative incidence may be a sign of approaching herd immunity, adherence to health protocols is still recommended due to the potential role of asymptomatic cases in transmitting the disease to other members of the community; and the presence of new variants of the virus and reduced antibody levels should be considered.
