{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,9]],"date-time":"2026-01-09T20:29:58Z","timestamp":1767990598383,"version":"3.49.0"},"reference-count":25,"publisher":"Public Library of Science (PLoS)","issue":"8","license":[{"start":{"date-parts":[[2023,8,16]],"date-time":"2023-08-16T00:00:00Z","timestamp":1692144000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Bio & Medical Technology Development Program of the National Research Foundation","award":["2021M3E5E3080382 and 2021R1I1A3044483"],"award-info":[{"award-number":["2021M3E5E3080382 and 2021R1I1A3044483"]}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS ONE"],"abstract":"<jats:sec id=\"sec001\">\n<jats:title>Objectives<\/jats:title>\n<jats:p>Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine effectiveness in coronavirus disease (COVID-19) patients with breakthrough infections has not been established in South Korea. To address this, we assessed the impact of vaccination on symptom occurrence and viral load.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec002\">\n<jats:title>Methods<\/jats:title>\n<jats:p>We performed a retrospective cohort study of 9,030 COVID-19 patients enrolled between February and November 2021. The impact of vaccination on the incidence of symptoms and viral load as indicated by cycle threshold (Ct) values of <jats:italic>RdRp<\/jats:italic> and <jats:italic>E<\/jats:italic> genes was evaluated using relative risks (RRs) and 95% confidence intervals (95% CIs).<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec003\">\n<jats:title>Results<\/jats:title>\n<jats:p>Compared with unvaccinated patients, fully vaccinated patients were associated with a reduced symptom onset of cough, sputum, and myalgia in COVID-19 patients (RR (95% CI) = 0.86 (0.75\u20130.99) for cough; RR (95% CI) = 0.74 (0.56\u20130.98) for sputum; RR (95% CI) = 0.65 (0.53\u20130.79) for myalgia, respectively). Additionally, lower risk of high viral load, Ct value of <jats:italic>RdRp<\/jats:italic> gene &lt;15 or Ct value of <jats:italic>E<\/jats:italic> gene &lt;15, was observed especially in fully vaccinated patients younger than 40 years ((RR (95% CI) = 0.69 (0.49\u20130.96) for <jats:italic>RdRp<\/jats:italic> gene; (RR (95% CI) = 0.71 (0.53\u20130.95) for <jats:italic>E<\/jats:italic> gene).<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec004\">\n<jats:title>Conclusion<\/jats:title>\n<jats:p>SARS-CoV-2 vaccination was associated with a reduced risk of COVID-19 symptoms as well as decreased viral load, especially in patients younger than 40 years.<\/jats:p>\n<\/jats:sec>","DOI":"10.1371\/journal.pone.0290154","type":"journal-article","created":{"date-parts":[[2023,8,16]],"date-time":"2023-08-16T17:37:50Z","timestamp":1692207470000},"page":"e0290154","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":8,"title":["Vaccine effectiveness in symptom and viral load mitigation in COVID-19 breakthrough infections in South Korea"],"prefix":"10.1371","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6970-9374","authenticated-orcid":true,"given":"Jieun","family":"Jang","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hyopin","family":"Jeong","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bong-Hwa","family":"Kim","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sura","family":"An","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hye-Ryun","family":"Yang","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8099-8891","authenticated-orcid":true,"given":"Sunjoo","family":"Kim","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"340","published-online":{"date-parts":[[2023,8,16]]},"reference":[{"issue":"8","key":"pone.0290154.ref001","doi-asserted-by":"crossref","first-page":"727","DOI":"10.1056\/NEJMoa2001017","article-title":"A novel coronavirus from patients with pneumonia in China, 2019","volume":"382","author":"N Zhu","year":"2020","journal-title":"N Engl J Med"},{"key":"pone.0290154.ref002","unstructured":"World Health Organization. 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Microbiology"},{"issue":"1","key":"pone.0290154.ref018","doi-asserted-by":"crossref","first-page":"e17","DOI":"10.1016\/j.jinf.2021.04.038","article-title":"Effectiveness of BNT162b2 vaccine against the B.1.1.7 variant of SARS-CoV-2 among healthcare workers in Brescia, Italy","volume":"83","author":"E Sansone","year":"2021","journal-title":"J Infect"},{"key":"pone.0290154.ref019","doi-asserted-by":"crossref","first-page":"e224","DOI":"10.1017\/S0950268821002247","article-title":"Effectiveness of COVID-19 vaccine in preventing infection and disease severity: a case-control study from an Eastern State of India","volume":"149","author":"C Singh","year":"2021","journal-title":"Epidemiol Infect"},{"key":"pone.0290154.ref020","doi-asserted-by":"crossref","first-page":"103574","DOI":"10.1016\/j.ebiom.2021.103574","article-title":"The BNT162b2 vaccine effectiveness against new COVID-19 cases and complications of breakthrough cases: A nation-wide retrospective longitudinal multiple cohort analysis using individualised data","volume":"72","author":"A Glatman-Freedman","year":"2021","journal-title":"EBioMedicin"},{"key":"pone.0290154.ref021","doi-asserted-by":"crossref","first-page":"104249","DOI":"10.1016\/j.compbiomed.2021.104249","article-title":"Discovering symptom patterns of COVID-19 patients using association rule mining","volume":"131","author":"M Tandan","year":"2021","journal-title":"Comput Biol Med"},{"issue":"5","key":"pone.0290154.ref022","doi-asserted-by":"crossref","first-page":"790","DOI":"10.1038\/s41591-021-01316-7","article-title":"Initial report of decreased SARS-CoV-2 viral load after inoculation with the BNT162b2 vaccine","volume":"27","author":"M Levine-Tiefenbrun","year":"2021","journal-title":"Nat Med"},{"issue":"12","key":"pone.0290154.ref023","doi-asserted-by":"crossref","first-page":"2108","DOI":"10.1038\/s41591-021-01575-4","article-title":"Viral loads of Delta-variant SARS-CoV-2 breakthrough infections after vaccination and booster with BNT162b2","volume":"27","author":"M Levine-Tiefenbrun","year":"2021","journal-title":"Nat Med"},{"issue":"2","key":"pone.0290154.ref024","doi-asserted-by":"crossref","first-page":"183","DOI":"10.1016\/S1473-3099(21)00648-4","article-title":"Community transmission and viral load kinetics of the SARS-CoV-2 delta (B.1.617.2) variant in vaccinated and unvaccinated individuals in the UK: a prospective, longitudinal, cohort study","volume":"22","author":"A Singanayagam","year":"2022","journal-title":"Lancet Infect Dis"},{"key":"pone.0290154.ref025","doi-asserted-by":"crossref","first-page":"521","DOI":"10.3389\/fmed.2020.00521","article-title":"Evaluation of Four Commercial Kits for SARS-CoV-2 Real-Time Reverse-Transcription Polymerase Chain Reaction Approved by Emergency-Use-Authorization in Korea","volume":"7","author":"KH Hur","year":"2020","journal-title":"Front Med (Lausanne)"}],"container-title":["PLOS ONE"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0290154","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,8,16]],"date-time":"2023-08-16T17:38:02Z","timestamp":1692207482000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0290154"}},"subtitle":[],"editor":[{"given":"Engin","family":"Berber","sequence":"first","affiliation":[],"role":[{"role":"editor","vocabulary":"crossref"}]}],"short-title":[],"issued":{"date-parts":[[2023,8,16]]},"references-count":25,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2023,8,16]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0290154","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,8,16]]}}}