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
Veneti, Lamprini; Bøås, Håkon; Kristoffersen, Anja Bråthen; Stålcrantz, Jeanette; Bragstad, Karoline; Hungnes, Olav; Storm, Margrethe Larsdatter; Aasand, Nina Therese; Rø, Gunnar Øyvind Isaksson; Starrfelt, Jostein; Seppälä, Elina Marjukka; Kvåle, Reidar; Vold, Line; Nygård, Karin; Buanes, Eirik Alnes; Whittaker, Robert Neil
Journal article, Peer reviewed
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OriginalversjonEurosurveillance. 2022, 27 (4), pii=2200077. 10.2807/1560-7917.ES.2022.27.4.2200077
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%).