{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,30]],"date-time":"2026-04-30T00:28:22Z","timestamp":1777508902815,"version":"3.51.4"},"reference-count":24,"publisher":"Cambridge University Press (CUP)","license":[{"start":{"date-parts":[[2025,2,7]],"date-time":"2025-02-07T00:00:00Z","timestamp":1738886400000},"content-version":"unspecified","delay-in-days":37,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0"}],"content-domain":{"domain":["cambridge.org"],"crossmark-restriction":true},"short-container-title":["Epidemiol. Infect."],"published-print":{"date-parts":[[2025]]},"abstract":"<jats:title>Abstract<\/jats:title>\n\t  <jats:p>We aimed to identify risk factors related to COVID-19 reinfection in Hong Kong. We performed a population-based retrospective cohort study and reviewed case-based data on COVID-19 infections reported to the Centre for Health Protection from 8 January 2020 to 29 January 2023. We analyzed the epidemiology of COVID-19 infections and performed a Cox regression analysis. In this period, 3.32% (103,065\/3,106,579) of COVID-19 infections recorded were classified as reinfection. Compared with primarily infected cases, a higher proportion of re-infected cases had chronic diseases (33.54% vs. 27.27%) and were residents of residential care homes (RCH) (10.99% vs. 1.41%). The time interval between the two episodes ranged from 31 to 1,050\u00a0days (median 282\u00a0days). Cox regression analysis of Omicron cases with the adjustment of covariates showed that being female (Hazard Ratio [HR] 1.12, 95% CI 1.11\u20131.13), chronic diseases (HR 1.18, 95% CI 1.16\u20131.20) and RCH residents (HR 6.78, 95% CI 6.61\u20136.95) were associated with reinfection, while additional vaccination after primary infection was protective (HR 0.80, 95% CI 0.79\u20130.81). Further analytical studies on the risk factors and protectors of COVID-19 reinfection are needed to guide targeted interventions.<\/jats:p>","DOI":"10.1017\/s0950268825000172","type":"journal-article","created":{"date-parts":[[2025,2,7]],"date-time":"2025-02-07T03:53:26Z","timestamp":1738900406000},"update-policy":"https:\/\/doi.org\/10.1017\/policypage","source":"Crossref","is-referenced-by-count":3,"title":["Characteristics and risk factors associated with COVID-19 reinfection in Hong Kong: a retrospective cohort study"],"prefix":"10.1017","volume":"153","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-9371-3305","authenticated-orcid":false,"given":"Wenhua","family":"Lin","sequence":"first","affiliation":[{"name":"Communicable Disease Branch, Centre for Health Protection"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kin Hang","family":"Kung","sequence":"additional","affiliation":[{"name":"Communicable Disease Branch, Centre for Health Protection"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chung Lam","family":"Chan","sequence":"additional","affiliation":[{"name":"Communicable Disease Branch, Centre for Health Protection"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shuk Kwan","family":"Chuang","sequence":"additional","affiliation":[{"name":"Communicable Disease Branch, Centre for Health Protection"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ka Wing","family":"Au","sequence":"additional","affiliation":[{"name":"Communicable Disease Branch, Centre for Health Protection"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"56","published-online":{"date-parts":[[2025,2,7]]},"reference":[{"key":"S0950268825000172_r16","first-page":"302","article-title":"COVID-19 reinfection rate and related risk factors in Fars Province, Iran: A retrospective cohort study","volume":"48","author":"Tavakoli","year":"2023","journal-title":"Iranian Journal of Medical Sciences"},{"key":"S0950268825000172_r14","doi-asserted-by":"publisher","DOI":"10.3390\/v15040967"},{"key":"S0950268825000172_r22","doi-asserted-by":"publisher","DOI":"10.1001\/jamanetworkopen.2022.23917"},{"key":"S0950268825000172_r19","doi-asserted-by":"publisher","DOI":"10.1016\/j.jinf.2023.06.002"},{"key":"S0950268825000172_r4","doi-asserted-by":"publisher","DOI":"10.1016\/S1473-3099(22)00345-0"},{"key":"S0950268825000172_r6","doi-asserted-by":"publisher","DOI":"10.1186\/s12889-023-15626-7"},{"key":"S0950268825000172_r23","unstructured":"[23] (2022) Consensus Interim Recommendations on the Use of COVID-19 Vaccines in Hong Kong (As of 13 October 2022) In: Health Do (ed). Scientific Committee on Emerging and Zoonotic Diseases and Scientific Committee on Vaccine Preventable Diseases."},{"key":"S0950268825000172_r1","unstructured":"[1] (2023) Weekly epidemiological update on COVID-19 - 25 August 2023. Edition 157. 25 August 2023. World Health Organization. Available at https:\/\/www.who.int\/publications\/m\/item\/weekly-epidemiological-update-on-covid-19---30-august-2023 (accessed."},{"key":"S0950268825000172_r7","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMc2212117"},{"key":"S0950268825000172_r13","doi-asserted-by":"publisher","DOI":"10.3389\/fpubh.2022.884121"},{"key":"S0950268825000172_r18","article-title":"Reinfections in COVID-19 patients: Impact of virus genetic variability and host immunity","volume":"9","author":"Fakhroo","year":"2021","journal-title":"Vaccines (Basel)"},{"key":"S0950268825000172_r15","doi-asserted-by":"publisher","DOI":"10.3390\/arm91060041"},{"key":"S0950268825000172_r5","unstructured":"[5] (2023) Statistics on 5th wave of COVID-19. 27 July 2023. Centre for Health Protection of Department of Health of Hong Kong. Available at https:\/\/www.coronavirus.gov.hk\/pdf\/5th_wave_statistics\/5th_wave_statistics_20230727.pdf (accessed."},{"key":"S0950268825000172_r21","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa2118691"},{"key":"S0950268825000172_r11","doi-asserted-by":"crossref","first-page":"833","DOI":"10.1016\/S0140-6736(22)02465-5","article-title":"Past SARS-CoV-2 infection protection against re-infection: A systematic review and meta-analysis","volume":"401","author":"Team","year":"2023","journal-title":"Lancet"},{"key":"S0950268825000172_r20","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa2119497"},{"key":"S0950268825000172_r8","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa2203965"},{"key":"S0950268825000172_r12","doi-asserted-by":"publisher","DOI":"10.1016\/j.jinf.2022.01.012"},{"key":"S0950268825000172_r24","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa2119451"},{"key":"S0950268825000172_r3","unstructured":"[3] (2022) Consensus Interim Recommendations on the Use of COVID-19 Vaccines in Hong Kong (As of 6 April 2022). In: Health Do (ed). Scientific Committee on Emerging and Zoonotic Diseases and Scientific Committee on Vaccine Preventable Diseases."},{"key":"S0950268825000172_r17","doi-asserted-by":"publisher","DOI":"10.3346\/jkms.2023.38.e269"},{"key":"S0950268825000172_r9","doi-asserted-by":"publisher","DOI":"10.1016\/S1473-3099(22)00288-2"},{"key":"S0950268825000172_r10","doi-asserted-by":"publisher","DOI":"10.46234\/ccdcw2023.075"},{"key":"S0950268825000172_r2","doi-asserted-by":"publisher","DOI":"10.1016\/j.lanwpc.2023.100969"}],"container-title":["Epidemiology and Infection"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.cambridge.org\/core\/services\/aop-cambridge-core\/content\/view\/S0950268825000172","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,7]],"date-time":"2025-10-07T14:45:41Z","timestamp":1759848341000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.cambridge.org\/core\/product\/identifier\/S0950268825000172\/type\/journal_article"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025]]},"references-count":24,"alternative-id":["S0950268825000172"],"URL":"https:\/\/doi.org\/10.1017\/s0950268825000172","relation":{},"ISSN":["0950-2688","1469-4409"],"issn-type":[{"value":"0950-2688","type":"print"},{"value":"1469-4409","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025]]},"assertion":[{"value":"\u00a9 The Government of the Hong Kong Special Administrative Region, China, 2025. Published by Cambridge University Press","name":"copyright","label":"Copyright","group":{"name":"copyright_and_licensing","label":"Copyright and Licensing"}},{"value":"This is an Open Access article, distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives licence (http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0), which permits non-commercial re-use, distribution, and reproduction in any medium, provided that no alterations are made and the original article is properly cited. The written permission of Cambridge University Press must be obtained prior to any commercial use and\/or adaptation of the article.","name":"license","label":"License","group":{"name":"copyright_and_licensing","label":"Copyright and Licensing"}},{"value":"This content has been made available to all.","name":"free","label":"Free to read"}],"article-number":"e30"}}