key: cord-0848907-wh6jgaua authors: Ara, J.; Islam, M. S.; Kader, M. T. U.; Das, A.; Hasib, F. M. Y.; Rahman, T.; Das, S.; Chowdhury, M. A. H.; Das, G. B.; Chowdhury, S. title: Sero-prevalence of anti-SARS-CoV-2 antibodies in Chattogram Metropolitan Area, Bangladesh date: 2022-02-09 journal: nan DOI: 10.1101/2022.02.09.22270717 sha: 070927267860239e95a9cc4e377fb81d4d801797 doc_id: 848907 cord_uid: wh6jgaua 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. Chattogram, the port city of Bangladesh, is classified as a high-risk zone for SARS-CoV-2 contact 67 transmission and is one of the most crowded economic and trading centers [1] . On April 3, 2020, 68 Chattogram city witnessed its first Coronavirus Disease 2019 (COVID-19) positive case [2], 69 followed by the first death on 9 April [3] . The disease can manifest itself in various ways, from . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. it is necessary to put in place measures including risk management in the workplace, vulnerable 114 employee care, the development of an occupational surveillance system, and vaccination policy . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted February 9, 2022. both in the risk groups and community might assist in planning interventions efficiently. In this study, we reported population-based SARS-CoV-2 seropositivity among HCWs, indoor and 118 outdoor patients of various government and private hospitals, and garment workers of CMA, as 119 determined by enzyme-linked immunosorbent assay (ELISA). Moreover, we measured the 120 antibody titer, and both outcomes (seropositivity and antibody titer) were tested to know the 121 association of different factors. Study design and setting 124 From February to September 2021, we conducted a cross-sectional population-based study among 125 HCWs (e.g., doctors, nurses, hospital staff, ward boy, and cleaner), garment workers, and indoor 126 and outdoor patients (non-COVID-19) of six government and private hospitals each, and two 127 garment factories in CMA. All hospitals belonging to the study area were stratified according to 128 their affiliation status; government and private. From each stratum, six hospitals were randomly 129 selected. Sample size was calculated considering the following parameter: 0.65 proportion, 5% 130 margin of error, 95% confidence limit and design effect 2. Each organization's human resources 131 department provided a list of personnel. Following a simple random sampling technique, samples 132 were collected from a total of 748 respondents. 133 We interviewed participants to collect information after receiving written consent. Answering a 134 questionnaire and taking blood to test SARS CoV-2 antibodies were part of the study procedure. Our study followed a World Health Organization protocol for population-level COVID-19 136 antibody testing [35] . The questionnaire included sociodemographic details and factors . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted February 9, 2022. instructions. The assay is an enzyme-linked immunoassay (ELISA) that detects IgG against the 157 SARS-CoV-2. An index (Absorbance/Cutt-off) of <1 was interpreted as negative, 0.9 to 1.1 as . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. ; https://doi.org/10.1101/2022.02.09.22270717 doi: medRxiv preprint 8 158 borderline (retesting of these specimens in duplicates was done to confirm results), and ≥1 index 159 as positive. Per the manufacturer, the sensitivity and specificity of the assay for IgG are 93.8% and 160 97.3%, respectively. Positive and negative controls were included in all assay batches. Repeated 161 testing using the same specimen yielded the same interpretation. The concentration of IgG antibodies was determined by SARS-CoV-2 S1-RBD IgG (DiaSino® For instance, the number of days between the first dose of vaccine and quantification of antibody 179 titer was categorized as 'after one month' and 'after two months' and between the second dose of 180 vaccine and quantification of antibody titer was categorized as 'after two months', 'after four . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. ; https://doi.org/10.1101/2022.02.09.22270717 doi: medRxiv preprint 9 181 months' and 'after six months'. The number of days between the vaccination and the antibody titer 182 was achieved from the date of vaccination and sample collection. The prevalence estimates were 183 adjusted with the test kit performance (sensitivity and specificity), and the adjusted prevalence was 184 denoted as true prevalence. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. further analysis to minimize the bias due to vaccination strategy followed in Bangladesh (priority . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. ; https://doi.org/10.1101/2022.02.09.22270717 doi: medRxiv preprint 14 236 given to aged); details in Table 3 is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. Multivariable analysis (logistic regression) to determine the potential factors associated with 255 SARS-CoV-2 antibody-positive status in the study area . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. The multivariable logistic regression model identified two potential factors that might be 257 influencing the seropositivity of SARS-CoV-2 antibodies in the studied population. The chance of 258 being seropositive was 2.22 times higher in indoor/outdoor patients (p= 0.002) and 1.69 times for 259 garments workers than HCWs (p= 0.01). Further, both doses of vaccine receivers had a higher 260 chance of being positive (OR=174.02) than one dose (OR=2.34) or none dose receivers, and the 261 difference was statistically significant (p< 0.001) ( Table 5) . using an immunoassay test to detect antibodies in the Sitakunda sub-district (Chattogram district) . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. HCWs had a 48% positivity rate [40] . Moreover, we observed that, among the garment workers, 284 just under 20% received vaccines and just above 50% were seropositive, which might have majorly 285 been achieved from natural infections (Figure 1) . It might indicate their lack of awareness about 286 disease transmission and vaccination. 287 We found that the IgG antibody was produced in 61.66% of the participants who received the first . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. Subsequently, when we quantified the antibody titer, we observed it higher in those who received 292 the second dose than in those who received just the first. Detection of highly avid anti-S1/-RBD 293 IgG, independent of the causal mechanism, is seen as a very positive indication and indicator of 294 enhanced humoral immunity [42] . Human coronavirus infection may not always result in long-lasting antibody responses, with 296 antibody titers dropping over time [43] . The waning of antibody responses is an essential element 297 to consider while developing a coronavirus vaccine [44] . Our study showed that by the second 298 month following the initial dose, the mean IgG titer in the body had dropped by nearly 25%. However, the antibody's propensity to deteriorate with time was noteworthy. This study revealed 300 that the available mean antibody titers that remained after two months of receiving the second dose 301 had dropped by roughly 21% by the fourth month, and within the sixth month the mean antibody is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. The study also revealed that people aged above 35 had a greater seroprevalence. Higher . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. Our study has several limitations, such as the fact that we only collected samples from hospitals 337 and the garment industry, but the results would be more representative of the community if we 338 included other groups. We could not compare immunological responses produced by different 339 COVID-19 vaccine brands at the same post-vaccination interval since distinct COVID-19 vaccines 340 were licensed and supplied to CMA at different times. We did not reveal the type and name of 341 COVID-19 vaccines, whereas a sufficient fraction was not covered under the vaccination program, 342 and we were concerned about an infodemic. CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted February 9, 2022. ; https://doi.org/10.1101/2022.02.09.22270717 doi: medRxiv preprint Molecular detection and prevalence of SARS-CoV-2 during the 374 early outbreak in southern Bangladesh Dhaka Tribune, First Coronavirus Case Confirmed in Chittagong, 6 Buildings in Lockdown Protecting our healthcare workers during the COVID-457 19 pandemic. The American journal of emergency medicine No patient safety without health worker 459 safety. The Lancet Mental health effects of COVID-19 461 pandemia: a review of clinical and psychological traits. Psychiatry investigation Export scenario between Bangladesh and China: Opportunities of 464 Bangladesh in RMG Sector Garment employees are at higher risk than any other 466 workers in COVID-19 pandemic in Bangladesh. Caspian Journal of Health Research COVID-19 among workers in meat and poultry processing facilities-19 states MMWR. 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CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 9, 2022. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)The copyright holder for this preprint this version posted February 9, 2022. ; https://doi.org/10.1101/2022.02.09.22270717 doi: medRxiv preprint