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. 2022 Jan;27(4):2200077.
doi: 10.2807/1560-7917.ES.2022.27.4.2200077.

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

Lamprini Veneti  1 , Håkon Bøås  2 , Anja Bråthen Kristoffersen  3 , Jeanette Stålcrantz  2   4 , Karoline Bragstad  5 , Olav Hungnes  5 , Margrethe Larsdatter Storm  6 , Nina Aasand  6 , Gunnar Rø  3 , Jostein Starrfelt  1 , Elina Seppälä  2 , Reidar Kvåle  7   8 , Line Vold  1 , Karin Nygård  1 , Eirik Alnes Buanes  7   9 , Robert Whittaker  2
Affiliations

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

Lamprini Veneti et al. Euro Surveill. 2022 Jan.

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%).

Keywords: B.1.1.529; COVID-19; Delta; Norway; Omicron; hospitalisation.

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Conflict of interest statement

Conflict of interest: None declared.

Figures

Figure 1
Figure 1
Proportion of reported COVID-19 cases with data on virus variant, and proportion of Delta and Omicron by week of sampling, Norway, 1 November 2021–9 January 2022 (n = 239,391)
Figure 2
Figure 2
10-day average case COVID-19 hospitalisation rate (unadjusted) as a function of time, Norway, 1 November 2021– 9 January 2022 (n = 239,391)
See this image and copyright information in PMC

References

    1. Brandal LT, MacDonald E, Veneti L, Ravlo T, Lange H, Naseer U, et al. Outbreak caused by the SARS-CoV-2 Omicron variant in Norway, November to December 2021. Euro Surveill. 2021;26(50):2101147. 10.2807/1560-7917.ES.2021.26.50.2101147 - DOI - PMC - PubMed
    1. Norwegian Institute of Public Health (FHI). Ukerapport uke 2 (10.01 - 16.01.22): Ukerapporter om koronavirus og covid-19. [Weekly report week 2 (10–16 Jan 2022): Weekly reports about coronavirus and COVID-19]. Oslo: FHI; 2022. Norwegian. Available from: https://www.fhi.no/contentassets/8a971e7b0a3c4a06bdbf381ab52e6157/vedleg...
    1. Norwegian Institute of Public Health (FHI). Ukerapport uke 52 (27.12.21 - 02.01.22): Ukerapporter om koronavirus og covid-19. [Weekly report week 52 (27 Dec 2021–2 Jan 2022): Weekly reports about coronavirus and COVID-19]. Oslo: FHI; 2022. Norwegian. Available from: https://www.fhi.no/contentassets/8a971e7b0a3c4a06bdbf381ab52e6157/vedleg...
    1. Norwegian Institute of Public Health (FHI). Emergency preparedness register for COVID-19 (Beredt C19). Oslo: FHI; 2021. Available from: https://www.fhi.no/en/id/infectious-diseases/coronavirus/emergency-prepa...
    1. Statens Serum Institut (SSI). Status of the SARS-CoV-2 variant Omicron in Denmark. Copenhagen: SSI; 2022. Available from: https://files.ssi.dk/covid19/omikron/statusrapport/rapport-omikronvarian...

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