{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,14]],"date-time":"2026-04-14T01:31:07Z","timestamp":1776130267927,"version":"3.50.1"},"reference-count":34,"publisher":"Wiley","issue":"2","license":[{"start":{"date-parts":[[2021,11,9]],"date-time":"2021-11-09T00:00:00Z","timestamp":1636416000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100006095","name":"Helse S\u00f8r-\u00d8st RHF","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100006095","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":[[2022,3]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Background<\/jats:title><jats:p>Infection with the novel coronavirus SARS\u2010CoV\u20102 induces antibodies that can be used as a proxy for COVID\u201019. We present a repeated nationwide cross\u2010sectional study assessing the seroprevalence of SARS\u2010CoV\u20102, the infection fatality rate (IFR), and infection hospitalization rate (IHR) during the first year of the pandemic in Norway.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Residual serum samples were solicited in April\/May 2020 (Round 1), in July\/August 2020 (Round 2) and in January 2021 (Round 3). Antibodies against SARS\u2010CoV\u20102 were measured using a flow cytometer\u2010based assay. Aggregate data on confirmed cases, COVID\u201019\u2010associated deaths and hospitalizations were obtained from the Emergency preparedness registry for COVID\u201019 (Beredt C19), and the seroprevalence estimates were used to estimate IFR and IHR.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Antibodies against SARS\u2010CoV\u20102 were measured in 4840 samples. The estimated seroprevalence increased from 0.8% (95% credible interval [CrI] 0.4%\u20131.3%) after the first wave of the pandemic (Rounds 1 and 2 combined) to 3.2% (95% CrI 2.3%\u20134.2%) (Round 3). The IFR and IHR were higher in the first wave than in the second wave and increased with age. The IFR was 0.2% (95% CrI 0.1%\u20130.3%), and IHR was 0.9% (95% CrI 0.6%\u20131.5%) for the second wave.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>The seroprevalence estimates show a cumulative increase of SARS\u2010CoV\u20102 infections over time in the Norwegian population and suggest some under\u2010recording of confirmed cases. The IFR and IHR were low, corresponding to the relatively low number of COVID\u201019\u2010associated deaths and hospitalizations in Norway. Most of the Norwegian population was still susceptible to SARS\u2010CoV\u20102 infection after the first year of the pandemic.<\/jats:p><\/jats:sec>","DOI":"10.1111\/irv.12932","type":"journal-article","created":{"date-parts":[[2021,11,9]],"date-time":"2021-11-09T10:14:37Z","timestamp":1636452877000},"page":"204-212","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Trends in seroprevalence of SARS\u2010CoV\u20102 and infection fatality rate in the Norwegian population through the first year of the COVID\u201019 pandemic"],"prefix":"10.1111","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8280-8243","authenticated-orcid":false,"given":"Gro","family":"Tunheim","sequence":"first","affiliation":[{"name":"Division of Infection Control Norwegian Institute of Public Health  Oslo Norway"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gunnar \u00d8yvind Isaksson","family":"R\u00f8","sequence":"additional","affiliation":[{"name":"Division of Infection Control Norwegian Institute of Public Health  Oslo Norway"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Trung","family":"Tran","sequence":"additional","affiliation":[{"name":"Department of Immunology Oslo University Hospital Rikshospitalet, University of Oslo  Oslo Norway"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Anne\u2010Marte Bakken","family":"Kran","sequence":"additional","affiliation":[{"name":"Division of Infection Control Norwegian Institute of Public Health  Oslo Norway"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jan Terje","family":"Andersen","sequence":"additional","affiliation":[{"name":"Department of Immunology Oslo University Hospital Rikshospitalet, University of Oslo  Oslo Norway"},{"name":"Department of Pharmacology, Institute of Clinical Medicine University of Oslo  Oslo Norway"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Eline Benno","family":"Vaage","sequence":"additional","affiliation":[{"name":"Department of Immunology Oslo University Hospital Rikshospitalet, University of Oslo  Oslo Norway"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Anette","family":"Kolderup","sequence":"additional","affiliation":[{"name":"Department of Immunology Oslo University Hospital Rikshospitalet, University of Oslo  Oslo Norway"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"John Torgils","family":"Vaage","sequence":"additional","affiliation":[{"name":"Department of Immunology Oslo University Hospital Rikshospitalet, University of Oslo  Oslo Norway"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fridtjof","family":"Lund\u2010Johansen","sequence":"additional","affiliation":[{"name":"Department of Immunology Oslo University Hospital Rikshospitalet, University of Oslo  Oslo Norway"},{"name":"ImmunoLingo Convergence Centre University of Oslo  Oslo Norway"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Olav","family":"Hungnes","sequence":"additional","affiliation":[{"name":"Division of Infection Control Norwegian Institute of Public Health  Oslo Norway"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2021,11,9]]},"reference":[{"key":"e_1_2_9_2_1","unstructured":"World Health Organization (WHO).Timeline of WHO's response to COVID\u201019.2020.https:\/\/www.who.int\/news\/item\/29-06-2020-covidtimeline. Accessed 13.12.20."},{"key":"e_1_2_9_3_1","unstructured":"Folkehelseinstituttet.Ukerapport\u2014uke 9.https:\/\/www.fhi.no: Folkehelseinstituttet; 10.03.21 2021."},{"key":"e_1_2_9_4_1","unstructured":"Folkehelseinstituttet.Ukerapport\u2014uke 18.https:\/\/www.fhi.no: Folkehelseinstituttet; tirsdag 19. mai 2020 2020."},{"key":"e_1_2_9_5_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.hlpt.2020.08.004"},{"key":"e_1_2_9_6_1","doi-asserted-by":"publisher","DOI":"10.2807\/1560-7917.ES.2021.26.1.2002023"},{"key":"e_1_2_9_7_1","doi-asserted-by":"publisher","DOI":"10.1002\/rmv.2162"},{"key":"e_1_2_9_8_1","doi-asserted-by":"publisher","DOI":"10.2807\/ese.15.31.19633-en"},{"key":"e_1_2_9_9_1","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.2010540117"},{"key":"e_1_2_9_10_1","doi-asserted-by":"publisher","DOI":"10.1111\/rssc.12435"},{"key":"e_1_2_9_11_1","unstructured":"Folkehelseinstituttet.Seroprevalence of SARS\u2010CoV\u20102 in the Norwegian population measured in residual sera collected in April\/May 2020 and August 2019.2020.https:\/\/www.fhi.no26.06.20 2020."},{"key":"e_1_2_9_12_1","unstructured":"Folkehelseinstituttet.Seroprevalence of SARS\u2010CoV\u20102 in the Norwegian population measured in residual sera collected in late summer 2020.2020.https:\/\/www.fhi.no09.06.21 2020."},{"key":"e_1_2_9_13_1","unstructured":"Folkehelseinstituttet.Seroprevalence of SARS\u2010CoV\u20102 in the Norwegian population measured in residual sera collected in January 2021.2021.https:\/\/www.fhi.no2021"},{"key":"e_1_2_9_14_1","unstructured":"Stan Development Team.Stan modelling language users guide and reference manual[computer program]. Version 2.26: Stan Development Team;2021."},{"key":"e_1_2_9_15_1","unstructured":"Stan Development Team.RStan: The R interface to Stan. R package[computer program]. Version 2.14.2: Stan Development Team;2020."},{"key":"e_1_2_9_16_1","doi-asserted-by":"crossref","unstructured":"VaselliNM HungerfordD ShentonB KhashkhushaA CunliffeNA FrenchN.The seroprevalence of SARS\u2010CoV\u20102 in Europe: a systematic review. bioRxiv.2021:2021.2004.2012.439425.https:\/\/doi.org\/10.1101\/2021.04.12.439425","DOI":"10.1101\/2021.04.12.439425"},{"key":"e_1_2_9_17_1","doi-asserted-by":"crossref","unstructured":"EspenhainL TriblerS J\u00f8rgensenCS Holm HansenC Wolff S\u00f6nksenU EthelbergS.Prevalence of SARS\u2010CoV\u20102 antibodies in Denmark 2020: results from nationwide population\u2010based sero\u2010epidemiological surveys medRxiv.2021:2021.2004.2007.21254703.https:\/\/doi.org\/10.1101\/2021.04.07.21254703","DOI":"10.1101\/2021.04.07.21254703"},{"key":"e_1_2_9_18_1","unstructured":"Folkehelseinstituttet.Ukerapport\u2014uke 20.https:\/\/www.fhi.no: Folkehelseinstituttet; tirsdag 19. mai 20202020."},{"key":"e_1_2_9_19_1","unstructured":"Folkehelseinstituttet.Ukerapport\u2014uke 31.https:\/\/www.fhi.no: Folkehelseinstituttet;2020."},{"key":"e_1_2_9_20_1","unstructured":"Folkehelseinstituttet.Ukerapport\u2014uke 52.https:\/\/www.fhi.no: Folkehelseinstituttet;2020."},{"key":"e_1_2_9_21_1","unstructured":"Folkehelseinstituttet.Resultater fra MoBa og Norflu\u2014Hvor mange har v\u00e6rt smittet med koronavirus i Oslo og omegn?2020.https:\/\/www.fhi.no\/studier\/prevalensundersokelser-korona\/resultat---moba\/. Accessed 09.06.21."},{"key":"e_1_2_9_22_1","doi-asserted-by":"crossref","unstructured":"AndaEE BraatenT BorchKB et al.Seroprevalence of antibodies against SARS\u2010CoV\u20102 virus in the adult Norwegian population winter 2020\/2021: pre\u2010vaccination period. medRxiv.2021:2021.2003.2023.21253730.https:\/\/doi.org\/10.1101\/2021.03.23.21253730v1","DOI":"10.1101\/2021.03.23.21253730"},{"key":"e_1_2_9_23_1","doi-asserted-by":"publisher","DOI":"10.1159\/000312871"},{"key":"e_1_2_9_24_1","doi-asserted-by":"publisher","DOI":"10.1503\/cmaj.110506"},{"key":"e_1_2_9_25_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijid.2020.09.1464"},{"key":"e_1_2_9_26_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41586-020-2918-0"},{"key":"e_1_2_9_27_1","article-title":"SARS\u2010CoV\u20102 infection fatality rate among elderly retired Danish blood donors\u2014a cross\u2010sectional study","author":"Pedersen OB","year":"2020","journal-title":"Clin Infect Dis"},{"key":"e_1_2_9_28_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.amjmed.2021.01.020"},{"key":"e_1_2_9_29_1","unstructured":"Folkehelseinstituttet.2021.01.06 National and regional corona report.https:\/\/www.fhi.no: Folkehelseinstituttet; 2021.01.062021."},{"key":"e_1_2_9_30_1","doi-asserted-by":"crossref","unstructured":"BoehmeKW KennedyJL SnowdenJet al.Pediatric SARS\u2010CoV\u20102 seroprevalence in Arkansas over the first year of the COVID\u201019 pandemic. medRxiv.2021:2021.2008.2004.21261592.https:\/\/doi.org\/10.1101\/2021.08.04.21261592","DOI":"10.1101\/2021.08.04.21261592"},{"key":"e_1_2_9_31_1","doi-asserted-by":"publisher","DOI":"10.1002\/ppul.24885"},{"key":"e_1_2_9_32_1","doi-asserted-by":"publisher","DOI":"10.3390\/ijerph18094640"},{"key":"e_1_2_9_33_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41591-020-0965-6"},{"key":"e_1_2_9_34_1","doi-asserted-by":"publisher","DOI":"10.1126\/science.abf4063"},{"key":"e_1_2_9_35_1","doi-asserted-by":"publisher","DOI":"10.1093\/cid\/ciab004"}],"container-title":["Influenza and Other Respiratory Viruses"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1111\/irv.12932","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/full-xml\/10.1111\/irv.12932","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1111\/irv.12932","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,8,28]],"date-time":"2023-08-28T10:45:22Z","timestamp":1693219522000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1111\/irv.12932"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,11,9]]},"references-count":34,"journal-issue":{"issue":"2","published-print":{"date-parts":[[2022,3]]}},"alternative-id":["10.1111\/irv.12932"],"URL":"https:\/\/doi.org\/10.1111\/irv.12932","archive":["Portico"],"relation":{},"ISSN":["1750-2640","1750-2659"],"issn-type":[{"value":"1750-2640","type":"print"},{"value":"1750-2659","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,11,9]]},"assertion":[{"value":"2021-09-16","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2021-10-26","order":1,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2021-11-09","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}