Nationwide seroprevalence of antibodies to SARS-CoV-2 in asymptomatic population in South Korea: a cross-sectional study

Objective Asymptomatic active infection might be an important contributor to the COVID-19 outbreak. Serological tests can assess the extent of exposure and herd immunity to COVID-19 in general populations. This study aimed to estimate the nationwide seroprevalence of SARS-CoV-2 antibodies according...

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Main Authors: Eun-Hee Nah, Seon Cho, Han-Ik Cho, Hyeran Park, Inhwan Hwang
Format: Article
Language:English
Published: BMJ Publishing Group 2021-04-01
Series:BMJ Open
Online Access:https://bmjopen.bmj.com/content/11/4/e049837.full
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author Eun-Hee Nah
Seon Cho
Han-Ik Cho
Hyeran Park
Inhwan Hwang
author_facet Eun-Hee Nah
Seon Cho
Han-Ik Cho
Hyeran Park
Inhwan Hwang
author_sort Eun-Hee Nah
collection DOAJ
description Objective Asymptomatic active infection might be an important contributor to the COVID-19 outbreak. Serological tests can assess the extent of exposure and herd immunity to COVID-19 in general populations. This study aimed to estimate the nationwide seroprevalence of SARS-CoV-2 antibodies according to age, sex and clinical status in South Korea.Design, setting and participants This cross-sectional study randomly selected health examinees who underwent health check-up at 16 health promotion centres in 13 Korean cities across the country between late September and early December 2020. Residual serum samples were obtained from 4085 subjects (2014 men and 2071 women). Antibodies to SARS-CoV-2 were measured by electrochemiluminescence immunoassay using Elecsys Anti-SARS-CoV-2 (Roche Elecsys, Mannheim, Germany).Primary and secondary outcome measures Fisher’s exact test was used to compare the seroprevalence according to sex, age group and region. The relative risks of being seropositive according to the characteristics of the study subjects were analysed using logistic regression analysis.Results The overall seroprevalence of anti-SARS-CoV-2 was 0.39% (95% CI=0.20% to 0.58%): 0.30% (95% CI=0.06% to 0.54%) for men and 0.48% (95% CI=0.18% to 0.78%) for women. The rate of anti-SARS-CoV-2 positivity varied significantly between different regions of Korea (p=0.003), but not with age group, sex, or the statuses of obesity, diabetes, hypertension or smoking.Conclusions Most of the Korean population is still immunologically vulnerable to SARS-CoV-2, but the seroprevalence has increased relative to that found in studies performed prior to September 2020 in Korea.
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spelling doaj-art-b75d5d0587b043789a65f084b6f7dc7c2025-08-20T02:32:42ZengBMJ Publishing GroupBMJ Open2044-60552021-04-0111410.1136/bmjopen-2021-049837Nationwide seroprevalence of antibodies to SARS-CoV-2 in asymptomatic population in South Korea: a cross-sectional studyEun-Hee Nah0Seon Cho1Han-Ik Cho2Hyeran Park3Inhwan Hwang4Department of Laboratory Medicine, Health Promotion Research Institute, Seoul, Korea (the Republic of)Department of Laboratory Medicine, Health Promotion Research Institute, Seoul, Korea (the Republic of)MEDIcheck LAB, Korea Association of Health Promotion, Seoul, South KoreaHealth Promotion Research Institute, Korea Association of Health Promotion, Seoul, Republic of KoreaHealth Promotion Research Institute, Korea Association of Health Promotion, Seoul, Republic of KoreaObjective Asymptomatic active infection might be an important contributor to the COVID-19 outbreak. Serological tests can assess the extent of exposure and herd immunity to COVID-19 in general populations. This study aimed to estimate the nationwide seroprevalence of SARS-CoV-2 antibodies according to age, sex and clinical status in South Korea.Design, setting and participants This cross-sectional study randomly selected health examinees who underwent health check-up at 16 health promotion centres in 13 Korean cities across the country between late September and early December 2020. Residual serum samples were obtained from 4085 subjects (2014 men and 2071 women). Antibodies to SARS-CoV-2 were measured by electrochemiluminescence immunoassay using Elecsys Anti-SARS-CoV-2 (Roche Elecsys, Mannheim, Germany).Primary and secondary outcome measures Fisher’s exact test was used to compare the seroprevalence according to sex, age group and region. The relative risks of being seropositive according to the characteristics of the study subjects were analysed using logistic regression analysis.Results The overall seroprevalence of anti-SARS-CoV-2 was 0.39% (95% CI=0.20% to 0.58%): 0.30% (95% CI=0.06% to 0.54%) for men and 0.48% (95% CI=0.18% to 0.78%) for women. The rate of anti-SARS-CoV-2 positivity varied significantly between different regions of Korea (p=0.003), but not with age group, sex, or the statuses of obesity, diabetes, hypertension or smoking.Conclusions Most of the Korean population is still immunologically vulnerable to SARS-CoV-2, but the seroprevalence has increased relative to that found in studies performed prior to September 2020 in Korea.https://bmjopen.bmj.com/content/11/4/e049837.full
spellingShingle Eun-Hee Nah
Seon Cho
Han-Ik Cho
Hyeran Park
Inhwan Hwang
Nationwide seroprevalence of antibodies to SARS-CoV-2 in asymptomatic population in South Korea: a cross-sectional study
BMJ Open
title Nationwide seroprevalence of antibodies to SARS-CoV-2 in asymptomatic population in South Korea: a cross-sectional study
title_full Nationwide seroprevalence of antibodies to SARS-CoV-2 in asymptomatic population in South Korea: a cross-sectional study
title_fullStr Nationwide seroprevalence of antibodies to SARS-CoV-2 in asymptomatic population in South Korea: a cross-sectional study
title_full_unstemmed Nationwide seroprevalence of antibodies to SARS-CoV-2 in asymptomatic population in South Korea: a cross-sectional study
title_short Nationwide seroprevalence of antibodies to SARS-CoV-2 in asymptomatic population in South Korea: a cross-sectional study
title_sort nationwide seroprevalence of antibodies to sars cov 2 in asymptomatic population in south korea a cross sectional study
url https://bmjopen.bmj.com/content/11/4/e049837.full
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