{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,10]],"date-time":"2026-02-10T18:52:58Z","timestamp":1770749578805,"version":"3.50.0"},"reference-count":43,"publisher":"Wiley","issue":"6","license":[{"start":{"date-parts":[[2025,6,3]],"date-time":"2025-06-03T00:00:00Z","timestamp":1748908800000},"content-version":"vor","delay-in-days":2,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","award":["NRF\u20102020R1I1A3066471"],"award-info":[{"award-number":["NRF\u20102020R1I1A3066471"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Influenza Resp Viruses"],"published-print":{"date-parts":[[2025,6]]},"abstract":"<jats:title>ABSTRACT<\/jats:title><jats:sec><jats:title>Background<\/jats:title><jats:p>Monitoring immunity levels nationwide and identifying disparities are important to prepare for future pandemics. However, data regarding changes in the seroprevalence of SARS\u2010CoV\u20102 and disparities in consecutive epidemic waves using existing surveillance systems are limited.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>We conducted a cross\u2010sectional serosurvey using 11,506 residual serum samples collected from the Korean National Health and Nutrition Examination Survey between January 2021 and December 2022. Antibodies to the SARS\u2010CoV\u20102 spike (anti\u2010S) protein, indicative of vaccination or past infection of SARS\u2010CoV\u20102, and nucleocapsid (anti\u2010N) protein, indicating infection, were quantified. Then, we applied post\u2010stratification weighting through the bootstrap resampling based on the age and sex distribution of the South Korean population. We used regression models to identify any disparities in the seropositivity prevalence ratio (PR) across different epidemic waves of SARS\u2010CoV\u20102 and demographics in the population.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>We identified that the anti\u2010S seropositivity gradually increased after the COVID\u201019 vaccination rollout, whereas anti\u2010N seropositivity increased after the SARS\u2010CoV\u20102 Omicron variant was introduced in Korea. Anti\u2010S seropositivity PR was 0.12\u20130.76 times lower in individuals &lt;\u200918\u2009years than in elderly individuals \u2265\u200965\u2009years during Waves 4\u20135 (July 2021 to June 2022). Anti\u2010N seropositivity PR was 1.25\u20131.83 times higher in individuals less than 64\u2009years than in elderly individuals during Waves 5\u20137 (January 2022 to December 2022).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>Our findings provide insights into the dynamic changes in immunity levels among the Korean population after the COVID\u201019 vaccine rollout and the introduction of the Omicron variant. Identifying the disparity in seroprevalence in the study population during the pandemic by using the existing surveillance system provides helpful information to develop future pandemic preparedness plans for the population.<\/jats:p><\/jats:sec>","DOI":"10.1111\/irv.70117","type":"journal-article","created":{"date-parts":[[2025,6,4]],"date-time":"2025-06-04T05:28:48Z","timestamp":1749014928000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Seroprevalence Trends of Antibodies to SARS\u2010CoV\u20102 in South Korea, 2021\u20132022: A Repeated Cross\u2010Sectional Study"],"prefix":"10.1111","volume":"19","author":[{"given":"Ah\u2010Ra","family":"Kim","sequence":"first","affiliation":[{"name":"Division of Clinical Research for Vaccine, Center for Vaccine Research, National Institute of Infectious Diseases National Institute of Health  Cheongju South 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