{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,10]],"date-time":"2026-11-10T15:50:19Z","timestamp":1794325819791,"version":"4.9.0"},"reference-count":30,"publisher":"Wiley","issue":"8","license":[{"start":{"date-parts":[[2023,8,22]],"date-time":"2023-08-22T00:00:00Z","timestamp":1692662400000},"content-version":"vor","delay-in-days":21,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Influenza Resp Viruses"],"published-print":{"date-parts":[[2023,8]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>The severity of Severe Acute Respiratory Syndrome Coronavirus 2 infection varies with age and time. Here, we quantify how age\u2010specific risks of hospitalization, intensive care unit (ICU) admission, and death upon infection changed from February 2020 to June 2021 in the Netherlands.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>A series of large representative serology surveys allowed us to estimate age\u2010specific numbers of infections in three epidemic periods (late\u2010February 2020 to mid\u2010June 2020, mid\u2010June 2020 to mid\u2010February 2021, and mid\u2010February 2021 to late\u2010June 2021). We accounted for reinfections and breakthrough infections. Severity measures were obtained by combining infection numbers with age\u2010specific numbers of hospitalization, ICU admission, and excess all\u2010cause deaths.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>There was an accelerating, almost exponential, increase in severity with age in each period. The rate of increase with age was the highest for death and the lowest for hospitalization. In late\u2010February 2020 to mid\u2010June 2020, the overall risk of hospitalization upon infection was 1.5% (95% confidence interval [CI] 1.3\u20131.8%), the risk of ICU admission was 0.36% (95% CI: 0.31\u20130.42%), and the risk of death was 1.2% (95% CI: 1.0\u20131.4%). The risk of hospitalization was significantly increased in mid\u2010June 2020 to mid\u2010February 2021, while the risk of ICU admission remained stable over time. The risk of death decreased over time, with a significant drop among \u226570\u2010years\u2010olds in mid\u2010February 2021 to late\u2010June 2021; COVID\u201019 vaccination started early January 2021.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Whereas the increase in severity of Severe Acute Respiratory Syndrome Coronavirus 2 with age remained stable, the risk of death upon infection decreased over time. A significant drop in risk of death among elderly coincided with the introduction of COVID\u201019 vaccination.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1111\/irv.13174","type":"journal-article","created":{"date-parts":[[2023,8,22]],"date-time":"2023-08-22T21:33:45Z","timestamp":1692740025000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":16,"title":["Age\u2010specific severity of severe acute respiratory syndrome coronavirus 2\u00a0in February 2020 to June 2021 in the Netherlands"],"prefix":"10.1111","volume":"17","author":[{"given":"Pieter T.","family":"de Boer","sequence":"first","affiliation":[{"name":"Center for Infectious Disease Control National Institute for Public Health and the Environment (RIVM)  Bilthoven The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jan","family":"van de Kassteele","sequence":"additional","affiliation":[{"name":"Center for Infectious Disease Control National Institute for Public Health and the Environment (RIVM)  Bilthoven The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eric R. A.","family":"Vos","sequence":"additional","affiliation":[{"name":"Center for Infectious Disease Control National Institute for Public Health and the Environment (RIVM)  Bilthoven The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Liselotte","family":"van Asten","sequence":"additional","affiliation":[{"name":"Center for Infectious Disease Control National Institute for Public Health and the Environment (RIVM)  Bilthoven The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dave A.","family":"Dongelmans","sequence":"additional","affiliation":[{"name":"Department of Intensive Care Medicine Amsterdam UMC (location AMC)  Amsterdam The Netherlands"},{"name":"Amsterdam Public Health Research Institute  Amsterdam The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arianne B.","family":"van Gageldonk\u2010Lafeber","sequence":"additional","affiliation":[{"name":"Center for Infectious Disease Control National Institute for Public Health and the Environment (RIVM)  Bilthoven The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gerco","family":"den Hartog","sequence":"additional","affiliation":[{"name":"Center for Infectious Disease Control National Institute for Public Health and the Environment (RIVM)  Bilthoven The Netherlands"},{"name":"Laboratory of Medical Immunology Radboudumc  Nijmegen The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Agnetha","family":"Hofhuis","sequence":"additional","affiliation":[{"name":"Center for Infectious Disease Control National Institute for Public Health and the Environment (RIVM)  Bilthoven The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fiona","family":"van der Klis","sequence":"additional","affiliation":[{"name":"Center for Infectious Disease Control National Institute for Public Health and the Environment (RIVM)  Bilthoven The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dylan W.","family":"de Lange","sequence":"additional","affiliation":[{"name":"Intensive Care, University Medical Center Utrecht University of Utrecht  Utrecht The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lenny","family":"Stoeldraijer","sequence":"additional","affiliation":[{"name":"Statistics Netherlands  The Hague The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"name":"the RIVM COVID\u201019 epidemiology and surveillance team","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hester E.","family":"de Melker","sequence":"additional","affiliation":[{"name":"Center for Infectious Disease Control National Institute for Public Health and the Environment (RIVM)  Bilthoven The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eveline","family":"Geubbels","sequence":"additional","affiliation":[{"name":"Center for Infectious Disease Control National Institute for Public Health and the Environment (RIVM)  Bilthoven The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Susan","family":"van den Hof","sequence":"additional","affiliation":[{"name":"Center for Infectious Disease Control National Institute for Public Health and the Environment (RIVM)  Bilthoven The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jacco","family":"Wallinga","sequence":"additional","affiliation":[{"name":"Center for Infectious Disease Control National Institute for Public Health and the Environment (RIVM)  Bilthoven The Netherlands"},{"name":"Department of Biomedical Data Sciences Leiden University Medical Center  Leiden The 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