ABSTRACT
Using individual-level national registry data, we conducted a cohort study to estimate differences in the length of hospital stay, and risk of admission to an intensive care unit and in-hospital death among patients infected with the SARS-CoV-2 Omicron variant, compared to patients infected with Delta variant in Norway. We included 409 (38%) patients infected with Omicron and 666 (62%) infected with Delta who were hospitalised with COVID-19 as the main cause of hospitalisation between 6 December 2021 and 6 February 2022. Omicron patients had a 48% lower risk of intensive care admission (aHR: 0.52, 95%CI: 0.34-0.80) and a 56% lower risk of in-hospital death (aHR: 0.44, 95%CI: 0.24-0.79) compared to Delta patients. Omicron patients had a shorter length of stay (with or without ICU stay) compared to Delta patients in the age groups from 18-79 years and those who had at least completed their primary vaccination. This supports growing evidence of reduced disease severity among hospitalised Omicron patients compared with Delta patients.
