{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,4]],"date-time":"2026-11-04T20:13:13Z","timestamp":1793823193757,"version":"4.6.1"},"reference-count":37,"publisher":"American Academy of Pediatrics (AAP)","issue":"3","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2022,9,1]]},"abstract":"<jats:sec>\n                    <jats:title>OBJECTIVES<\/jats:title>\n                    <jats:p>There is limited evidence on whether the relative severity of coronavirus disease 2019 (COVID-19) in children and adolescents differs for different severe acute respiratory syndrome coronavirus 2 variants. We compare the risk of hospitalization to acute COVID-19 or multisystem inflammatory syndrome in children (MIS-C) among unvaccinated persons &amp;lt;18 years with COVID-19 (cases) between waves of the Alpha, Delta, and Omicron (sublineage BA.1) variants in Norway.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>METHODS<\/jats:title>\n                    <jats:p>We used linked individual-level data from national registries to calculate adjusted risk ratios (aRR) with 95% confidence interval (CI) using multivariable log-binomial regression. We adjusted for variant wave, demographic characteristics, and underlying comorbidities.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>RESULTS<\/jats:title>\n                    <jats:p>We included 10\u2009538 Alpha (21 hospitalized with acute COVID-19, 7 MIS-C), 42\u2009362 Delta (28 acute COVID-19, 14 MIS-C), and 82\u2009907 Omicron wave cases (48 acute COVID-19, 7 MIS-C). The risk of hospitalization with acute COVID-19 was lower in the Delta (aRR: 0.53, 95% CI: 0.30\u20130.93) and Omicron wave (aRR: 0.40, 95% CI: 0.24\u20130.68), compared to the Alpha wave. We found no difference in this risk for Omicron compared to Delta. The risk of MIS-C was lower for Omicron, compared to Alpha (aRR: 0.09, 95% CI: 0.03\u20130.27) and Delta (aRR: 0.26, 95% CI: 0.10\u20130.63).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>CONCLUSIONS<\/jats:title>\n                    <jats:p>We do not find clear evidence that different variants have influenced the risk of hospitalization with acute COVID-19 among unvaccinated children and adolescents in Norway. The lower risk of this outcome with Omicron and Delta may reflect changes in other factors over time, such as the testing strategy, maternal vaccination and\/or hospitalization criteria. The emergence of Omicron has reduced the risk of MIS-C.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1542\/peds.2022-057564","type":"journal-article","created":{"date-parts":[[2022,8,2]],"date-time":"2022-08-02T04:15:23Z","timestamp":1659413723000},"source":"Crossref","is-referenced-by-count":33,"title":["COVID-19 Hospitalization Among Children &amp;lt;18 Years by Variant Wave in Norway"],"prefix":"10.1542","volume":"150","author":[{"given":"Robert","family":"Whittaker","sequence":"first","affiliation":[{"name":"aDepartments of Infection Control and Vaccines"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Margrethe","family":"Greve-Isdahl","sequence":"additional","affiliation":[{"name":"aDepartments of Infection Control and Vaccines"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"H\u00e5kon","family":"B\u00f8\u00e5s","sequence":"additional","affiliation":[{"name":"bInfection Control and Preparedness"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"P\u00e5l","family":"Suren","sequence":"additional","affiliation":[{"name":"cChild Health and Development, Norwegian Institute of Public Health, Oslo, Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eirik Alnes","family":"Buanes","sequence":"additional","affiliation":[{"name":"dDepartment of Anaesthesia and Intensive Care"},{"name":"eNorwegian Intensive Care and Pandemic Registry, Haukeland University Hospital, Bergen, Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lamprini","family":"Veneti","sequence":"additional","affiliation":[{"name":"bInfection Control and Preparedness"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"417","published-online":{"date-parts":[[2022,8,2]]},"reference":[{"key":"2023110816302417300_B1","unstructured":"World Health Organisation\n          . Tracking SARS-CoV-2 variants. Available at: https:\/\/www.who.int\/en\/activities\/tracking-SARS- CoV-2-variants\/. Accessed xx,xx,xxxx"},{"issue":"24","key":"2023110816302417300_B2","doi-asserted-by":"crossref","DOI":"10.2807\/1560-7917.ES.2021.26.24.2100509","article-title":"Increased transmissibility and global spread of SARS-CoV-2 variants of concern as at June 2021","volume":"26","author":"Campbell","year":"2021","journal-title":"Euro Surveill"},{"key":"2023110816302417300_B3","article-title":"SARS-CoV-2 Omicron VOC transmission in Danish households","author":"Lyngse","year":"2022","journal-title":"Medrxiv"},{"issue":"10","key":"2023110816302417300_B4","doi-asserted-by":"crossref","first-page":"e0258513","DOI":"10.1371\/journal.pone.0258513","article-title":"Increased risk of hospitalisation and intensive care admission associated with reported cases of SARS-CoV-2 variants B.1.1.7 and B.1.351 in Norway, December 2020 -May 2021","volume":"16","author":"Veneti","year":"2021","journal-title":"PLoS One"},{"issue":"10332","key":"2023110816302417300_B5","doi-asserted-by":"crossref","first-page":"1303","DOI":"10.1016\/S0140-6736(22)00462-7","article-title":"Comparative analysis of the risks of hospitalisation and death associated with SARS-CoV-2 omicron (B.1.1.529) and delta (B.1.617.2) variants in England: a cohort study","volume":"399","author":"Nyberg","year":"2022","journal-title":"Lancet"},{"issue":"7","key":"2023110816302417300_B6","doi-asserted-by":"crossref","first-page":"585","DOI":"10.1056\/NEJMoa2108891","article-title":"Effectiveness of Covid-19 vaccines against the B.1.617.2 (Delta) variant","volume":"385","author":"Lopez Bernal","year":"2021","journal-title":"N Engl J Med"},{"issue":"16","key":"2023110816302417300_B7","doi-asserted-by":"crossref","first-page":"1532","DOI":"10.1056\/NEJMoa2119451","article-title":"Covid-19 vaccine effectiveness against the omicron (B.1.1.529) variant","volume":"386","author":"Andrews","year":"2022","journal-title":"N Engl J Med"},{"issue":"4","key":"2023110816302417300_B8","doi-asserted-by":"crossref","DOI":"10.2807\/1560-7917.ES.2022.27.4.2200077","article-title":"Reduced risk of hospitalisation among reported COVID-19 cases infected with the SARS-CoV-2 Omicron BA.1 variant compared with the Delta variant, Norway, December 2021 to January 2022","volume":"27","author":"Veneti","year":"2022","journal-title":"Euro Surveill"},{"key":"2023110816302417300_B9","unstructured":"World Health Organisation\n          . COVID-19 weekly epidemiological update, Edition 81. 2022. Available at: https:\/\/www.who. int\/publications\/m\/item\/weekly- epidemiological-update-on-covid-19\u2013- 1-march-2022. Accessed March 22, 2022"},{"issue":"385","key":"2023110816302417300_B10","doi-asserted-by":"crossref","first-page":"n385","DOI":"10.1136\/bmj.n385","article-title":"Acute covid-19 and multisystem inflammatory syndrome in children","volume":"372","author":"Rubens","year":"2021","journal-title":"BMJ"},{"key":"2023110816302417300_B11","doi-asserted-by":"crossref","first-page":"101287","DOI":"10.1016\/j.eclinm.2022.101287","article-title":"Which children and young people are at higher risk of severe disease and death after hospitalisation with SARS-CoV-2 infection in children and young people: A systematic review and individual patient meta-analysis","volume":"44","author":"Harwood","year":"2022","journal-title":"EClinicalMedicine"},{"key":"2023110816302417300_B12","article-title":"Reduced risk of hospitalization associated with infection with SARS-CoV-2 Omicron relative to Delta: a Danish cohort study","author":"Bager","year":"2022","journal-title":"SSRN"},{"key":"2023110816302417300_B13","first-page":"e220945","article-title":"Incidence rates and clinical outcomes of SARS-CoV-2 infection with the Omicron and Delta variants in children younger than 5 years in the US","author":"Wang","year":"2022","journal-title":"JAMA Pediatr"},{"issue":"1","key":"2023110816302417300_B14","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1016\/S1473-3099(21)00475-8","article-title":"Hospital admission and emergency care attendance risk for SARS-CoV-2 delta (B.1.617.2) compared with alpha (B.1.1.7) variants of concern: a cohort study","volume":"22","author":"Twohig","year":"2022","journal-title":"Lancet Infect Dis"},{"issue":"42","key":"2023110816302417300_B15","doi-asserted-by":"crossref","first-page":"E1619","DOI":"10.1503\/cmaj.211248","article-title":"Evaluation of the relative virulence of novel SARS-CoV-2 variants: a retrospective cohort study in Ontario, Canada","volume":"193","author":"Fisman","year":"2021","journal-title":"CMAJ"},{"issue":"2","key":"2023110816302417300_B16","doi-asserted-by":"crossref","first-page":"e2143151","DOI":"10.1001\/jamanetworkopen.2021.43151","article-title":"Characteristics, outcomes, and severity risk factors associated with SARS-CoV-2 infection among children in the US national COVID cohort collaborative","volume":"5","author":"Martin","year":"2022","journal-title":"JAMA Netw Open"},{"issue":"5","key":"2023110816302417300_B17","doi-asserted-by":"crossref","first-page":"2050","DOI":"10.1002\/jmv.27587","article-title":"Evaluation of childhood hospitalization rates and degree of severity of SARS-CoV-2 variants, including B.1.1.7 (Alpha), B.1.315\/P.1 (Beta\/Gamma), and B.1.617.2 (Delta)","volume":"94","author":"Y\u0131lmaz \u00c7elebi","year":"2022","journal-title":"J Med Virol"},{"issue":"4","key":"2023110816302417300_B18","doi-asserted-by":"crossref","first-page":"591","DOI":"10.1016\/j.jiac.2022.01.009","article-title":"Comparison of the clinical characteristics and outcomes of COVID-19 in children before and after the emergence of Delta variant of concern in Japan","volume":"28","author":"Shoji","year":"2022","journal-title":"J Infect Chemother"},{"key":"2023110816302417300_B19","doi-asserted-by":"crossref","DOI":"10.2139\/ssrn.4031587","article-title":"Multisystem inflammatory syndrome in children following the SARS-CoV-2 delta variant in Denmark: clinical phenotype and risk by vaccination status and compared to the pre-Delta COVID-19 era","author":"Nygaard","year":"2022","journal-title":"SSRN"},{"key":"2023110816302417300_B20","unstructured":"SARS-CoV-2 hos b\u00f8rn (0-15 \u00e5r) i Danmark smitte, indl\u00e6ggelser og alvorlige forl\u00f8b; udviklingen siden 15. december 2021. Statens Serums Institut. Available at: https:\/\/www.ssi.dk\/-\/media\/cdn\/ files\/sarscov2_hos_boern_0-15_aar_i_ danmark_feb_2022.pdf?la=da. Accessed April 13, 2022"},{"key":"2023110816302417300_B21","article-title":"Lower risk of multisystem inflammatory syndrome in children (MIS-C) with the Delta and Omicron variants of SARS-CoV-2","author":"Cohen","year":"2022","journal-title":"Medrxiv"},{"key":"2023110816302417300_B22","doi-asserted-by":"crossref","first-page":"178","DOI":"10.1016\/j.ijid.2021.12.321","article-title":"No difference in risk of hospitalization between reported cases of the SARS-CoV-2 Delta variant and Alpha variant in Norway","volume":"115","author":"Veneti","year":"2022","journal-title":"Int J Infect Dis"},{"key":"2023110816302417300_B23","unstructured":"Norwegian Institute of Public Health\n          . Coronavirus vaccine - information for the public. Available at: https:\/\/www.fhi. no\/en\/id\/vaccines\/coronavirus- immunisation-programme\/who-will-get- coronavirus-vaccine-first\/. Accessed March 22, 2022"},{"key":"2023110816302417300_B24","unstructured":"Norwegian Institute of Public Health\n          . Emergency preparedness register for COVID-19 (Beredt C19). Available at: https:\/\/www.fhi.no\/en\/id\/infectious- diseases\/coronavirus\/emergency- preparedness-register-for-covid-19\/. Accessed March 22, 2022"},{"key":"2023110816302417300_B25","unstructured":"Norwegian Institute of Public Health\n          . P\u00e5visning og overv\u00e5kning av SARS-CoV-2-virusvarianter. Oslo: Norwegian Institute of Public Health. Available at: https:\/\/www.fhi.no\/nettpub\/coronavirus\/testing\/pavisning-og-overvakning-av-sars- cov-2-virusvarianter\/. Accessed March 22, 2022"},{"key":"2023110816302417300_B26","unstructured":"Norwegian Institute of Public Health\n          . Ukerapport uke 7 2022. Available at: https:\/\/www.fhi.no\/contentassets\/8a971e7b0a3c4a06bdbf381ab52e6157\/vedlegg\/2022\/ukerapport-uke-7-14.02\u2013- 20.02.22.pdf. Accessed March 22, 2022"},{"key":"2023110816302417300_B27","unstructured":"Norwegian Society of Pediatricians\n          . Inflammatorisk multisystemsyndrom ved covid-19 (MIS-C). Available at: https:\/\/www.helsebiblioteket.no\/pediatriveiledere? menuitemkeylev1=5962&menuitemkeylev2= 5966&key=271455. Accessed March 22, 2022"},{"key":"2023110816302417300_B28","first-page":"e221110","article-title":"Acute upper airway disease in children with the Omicron (B.1.1.529) variant of SARS-CoV-2-A report from the US National COVID Cohort Collaborative","author":"Martin","year":"2022","journal-title":"JAMA Pediatr"},{"issue":"6","key":"2023110816302417300_B29","doi-asserted-by":"crossref","first-page":"e2116420","DOI":"10.1001\/jamanetworkopen.2021.16420","article-title":"Incidence of multisystem inflammatory syndrome in children among US persons infected with SARS-CoV-2","volume":"4","author":"Payne","year":"2021","journal-title":"JAMA Netw Open"},{"issue":"9","key":"2023110816302417300_B30","doi-asserted-by":"crossref","first-page":"2581","DOI":"10.1111\/apa.15985","article-title":"Multisystem inflammatory syndrome in children occurred in one of four thousand children with severe acute respiratory syndrome coronavirus 2","volume":"110","author":"Holm","year":"2021","journal-title":"Acta Paediatr"},{"issue":"2","key":"2023110816302417300_B31","doi-asserted-by":"crossref","first-page":"52","DOI":"10.15585\/mmwr.mm7102e1","article-title":"Effectiveness of BNT162b2 (Pfizer-BioNTech) mRNA vaccination against multisystem inflammatory syndrome in children among persons aged 12-18 years - United States, July-December 2021","volume":"71","author":"Zambrano","year":"2022","journal-title":"MMWR Morb Mortal Wkly Rep"},{"issue":"1","key":"2023110816302417300_B32","doi-asserted-by":"crossref","first-page":"543","DOI":"10.1080\/22221751.2022.2035195","article-title":"Omicron variant susceptibility to neutralizing antibodies induced in children by natural SARS-CoV-2 infection or COVID-19 vaccine","volume":"11","author":"Chen","year":"2022","journal-title":"Emerg Microbes Infect"},{"issue":"9","key":"2023110816302417300_B33","doi-asserted-by":"crossref","first-page":"352","DOI":"10.15585\/mmwr.mm7109e3","article-title":"Effectiveness of COVID-19 Pfizer-BioNTech BNT162b2 mRNA vaccination in preventing COVID-19-associated emergency department and urgent care encounters and hospitalizations among nonimmunocompromised children and adolescents aged 5-17 Years - VISION Network, 10 States, April 2021-January 2022","volume":"71","author":"Klein","year":"2022","journal-title":"MMWR Morb Mortal Wkly Rep"},{"key":"2023110816302417300_B34","first-page":"ciab1007","article-title":"Multisystem inflammatory syndrome in children\u2013United States, February 2020-July 2021","author":"Miller","year":"2021","journal-title":"Clin Infect Dis"},{"issue":"7","key":"2023110816302417300_B35","doi-asserted-by":"crossref","first-page":"264","DOI":"10.15585\/mmwr.mm7107e3","article-title":"Effectiveness of maternal vaccination with mRNA COVID-19 vaccine during pregnancy against COVID-19-associated hospitalization in infants aged &lt;6 Months - 17 States, July 2021\u2013January 2022","volume":"71","author":"Halasa","year":"2022","journal-title":"MMWR Morb Mortal Wkly Rep"},{"issue":"1","key":"2023110816302417300_B36","doi-asserted-by":"crossref","first-page":"58","DOI":"10.1002\/phar.2649","article-title":"Role of maternal COVID-19 vaccination in providing immunological protection to the newborn","volume":"42","author":"Jorgensen","year":"2022","journal-title":"Pharmacotherapy"},{"issue":"8","key":"2023110816302417300_B37","doi-asserted-by":"crossref","first-page":"713","DOI":"10.1056\/NEJMoa2117995","article-title":"Effectiveness of BNT162b2 vaccine against Critical Covid-19 in adolescents","volume":"386","author":"Olson","year":"2022","journal-title":"N Engl J Med"}],"container-title":["Pediatrics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/publications.aap.org\/pediatrics\/article-pdf\/doi\/10.1542\/peds.2022-057564\/1561495\/peds_2022057564.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/publications.aap.org\/pediatrics\/article-pdf\/doi\/10.1542\/peds.2022-057564\/1561495\/peds_2022057564.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,11,8]],"date-time":"2023-11-08T11:34:00Z","timestamp":1699443240000},"score":1,"resource":{"primary":{"URL":"https:\/\/publications.aap.org\/pediatrics\/article\/150\/3\/e2022057564\/188698\/COVID-19-Hospitalization-Among-Children-lt-18"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,8,2]]},"references-count":37,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2022,8,2]]},"published-print":{"date-parts":[[2022,9,1]]}},"URL":"https:\/\/doi.org\/10.1542\/peds.2022-057564","relation":{"has-preprint":[{"id-type":"doi","id":"10.1101\/2022.03.29.22273093","asserted-by":"object"}]},"ISSN":["0031-4005","1098-4275"],"issn-type":[{"value":"0031-4005","type":"print"},{"value":"1098-4275","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,8,2]]},"article-number":"e2022057564"}}