Sero-prevalence of anti-SARS-CoV-2 antibodies in Chattogram Metropolitan Area, Bangladesh

Abstract

Background: Seroprevalence studies of coronavirus disease 2019 (COVID-19) assess the degree of undetected transmission in the community. Different groups, such as healthcare workers (HCWs), garment workers, and others, are deemed vulnerable due to their workplace hazards and immense responsibility. Purpose: The present study was conducted to estimate the seroprevalence of anti-SARS-CoV-2 antibody (IgG) and its association with different explanatory variables. Further, the antibody was quantified to assess the increasing or decreasing trend over different intervention periods and according to other factors. Methodology: This cross-sectional study observed health workers - doctor, nurse, hospital staff, etc. in and outpatients (non-COVID-19) and garments workers of Chattogram metropolitan area (CMA, N=748) from randomly selected six government and private hospitals and two garment factories. Study subjects were included upon written consent, fulfilling specific inclusion criteria. Venous blood was collected following standard aseptic methods. Qualitative and quantitative ELISA was used to identify and quantify antibodies (IgG) in serum samples. Descriptive, univariable, and multivariable statistical analysis was performed. Results: Overall seroprevalence was estimated as 66.99% (95% CI: 63.40%-70.40%). Seroprevalence among HCWs, in and outpatients, and garments workers were 68.99 % (95% CI: 63.8%-73.7%), 81.37 % (95% CI: 74.7%-86.7%), and 50.56 % (95% CI: 43.5%-57.5%), respectively. Seroprevalence was 44.47 % (95% CI: 38.6%-50.4%) in the non-vaccinated population while it was significantly ( p <0.001) higher in the population receiving the first dose (61.66 %, 95% CI: 54.8%-68.0%) and both (first and second) doses of vaccine (100%, 95% CI: 98.4%-100%). The mean titer of the antibody was estimated as 255.46 DU/ml and 159.08 DU/ml in the population with both doses and one dose of vaccine, respectively, compared to 53.71 DU/ml of the unvaccinated population. A decreasing trend in the titer of antibodies with increasing time after vaccination was observed. Conclusions: Seroprevalence and mean antibody titer varied according to different factors in this study. The second dose of vaccine significantly increased the seroprevalence and titer, which decreased to a certain level over time. Although antibody was produced following natural infection, the mean titer was relatively low compared to antibody after vaccination. This study emphasizes the role of the vaccine in antibody production. Based on the findings, interventions like continuing extensive mass vaccination of the leftover unvaccinated population and bringing the mass population with a second dose under a third dose campaign might be planned.

Diagnostic Performance of Five Rapid Serological Tests for SARS-CoV-2

“…Available data from serological tests allow an assessment of the level of circulation of the COVID-19 virus in the population [11]- [16]. In the field of epidemiology, it is important to know in advance the performance of new tests in the field, in order to increase the certainty of the presence or absence of the disease.…”

“…All of these conditions limit its widespread use in resource-limited countries [10]. Seroepidemiological studies conducted in several countries and particularly in African countries show that positive case statistics based entirely on screening PCR underestimate the true extent of SARS-CoV-2 virus circulation in populations [11]- [16]. On the other hand, a meta-analysis study conducted in 2020 to describe the performance of different antigenic and serological tests in the diagnosis of COVID-19, including 25 diagnostic tests out of a total of 2247 participants, showed that only one diagnostic test had better specificity and sensitivity [17].…”

“…On the other hand, a meta-analysis study conducted in 2020 to describe the performance of different antigenic and serological tests in the diagnosis of COVID-19, including 25 diagnostic tests out of a total of 2247 participants, showed that only one diagnostic test had better specificity and sensitivity [17]. The weak performance of serological tests may contribute to the paradox between the number of cases reported in Africa and the estimates of seroprevalence studies [11]- [16]. The best serological tests for the detection of COVID-19 disease should be those that have the ability to identify positive (sensitivity) and negative (specificity) subjects.…”

Seroepidemiology of SARS-CoV-2 Virus in Healthcare Workers before Circulation of the Omicron Sublineages BA.4/BA.5 in Vojvodina, Serbia

“…The highest seroprevalence rates were found in those HCWs who had previous infection(s) and were also vaccinated, but it remains unknown whether this hybrid immunity could translate into protection against the new variants of concern. In order to better understand the level of immunity to actual variants of SARS-CoV-2 and to plan interventions efficiently, the vaccination coverage and seroprevalence of SARS-CoV-2 in both the risk groups and the general community must be assessed in future perspectives [33]. Although our results in HCWs cannot be directly extrapolated to other population groups in Vojvodina and Serbia, it is reasonable to assume that the seroprevalence rates in the general population in our country are relatively high; future studies are warranted to delineate this.…”

Twice evasions of Omicron variants explain the temporal patterns in six Asia and Oceania countries

“…The seroprevalence study [31], which was conducted in Chattogram Metropolitan Area, Bangladesh from February to September 2021 based on the health worker, in and outpatients and garments workers, estimated the overall seroprevalence as 66.99% (95% CI: 63.40%-70.40%). There is another longitudinal cohort study [32] compared the serological response in patients with differing severity of COVID-19 infection.…”