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Abstract

We included 39,524 COVID-19 Omicron and 51,481 Delta cases reported in Norway from December 2021 to January 2022. We estimated a 73% reduced risk of hospitalisation (adjusted hazard ratio: 0.27; 95% confidence interval: 0.20–0.36) for Omicron compared with Delta. Compared with unvaccinated groups, Omicron cases who had completed primary two-dose vaccination 7–179 days before diagnosis had a lower reduced risk than Delta (66% vs 93%). People vaccinated with three doses had a similar risk reduction (86% vs 88%).

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/content/10.2807/1560-7917.ES.2022.27.4.2200077
2022-01-27
2024-11-21
http://instance.metastore.ingenta.com/content/10.2807/1560-7917.ES.2022.27.4.2200077
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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
<p class="citation"> <span>Citation style for this article:</span> <span class="meta-value authors"> <a href="/search?value1=Lamprini+Veneti&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Veneti Lamprini</a>, <a href="/search?value1=H%C3%A5kon+B%C3%B8%C3%A5s&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Bøås Håkon</a>, <a href="/search?value1=Anja+Br%C3%A5then+Kristoffersen&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Bråthen Kristoffersen Anja</a>, <a href="/search?value1=Jeanette+St%C3%A5lcrantz&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Stålcrantz Jeanette</a>, <a href="/search?value1=Karoline+Bragstad&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Bragstad Karoline</a>, <a href="/search?value1=Olav+Hungnes&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Hungnes Olav</a>, <a href="/search?value1=Margrethe+Larsdatter+Storm&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Storm Margrethe Larsdatter</a>, <a href="/search?value1=Nina+Aasand&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Aasand Nina</a>, <a href="/search?value1=Gunnar+R%C3%B8&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Rø Gunnar</a>, <a href="/search?value1=Jostein+Starrfelt&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Starrfelt Jostein</a>, <a href="/search?value1=Elina+Sepp%C3%A4l%C3%A4&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Seppälä Elina</a>, <a href="/search?value1=Reidar+Kv%C3%A5le&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Kvåle Reidar</a>, <a href="/search?value1=Line+Vold&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Vold Line</a>, <a href="/search?value1=Karin+Nyg%C3%A5rd&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Nygård Karin</a>, <a href="/search?value1=Eirik+Alnes+Buanes&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Buanes Eirik Alnes</a>, <a href="/search?value1=Robert+Whittaker&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Whittaker Robert</a></span>. 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. <a href="/content/ecdc">Euro Surveill.</a> 2022;27(4):pii=2200077. <a href="https://doi.org/10.2807/1560-7917.ES.2022.27.4.2200077" title="doi link" target="_blank">https://doi.org/10.2807/1560-7917.ES.2022.27.4.2200077</a> <span class="ES_Article_citation"> <span class="generated">Received</span>: 21 Jan 2022;&nbsp;&nbsp; <span class="generated">Accepted</span>: 25 Jan 2022 </span> </p>
/content/10.2807/1560-7917.ES.2022.27.4.2200077
/content/10.2807/1560-7917.ES.2022.27.4.2200077
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