SARS-CoV-2 variants of concern and variants under investigation in England Technical briefing: Update on hospitalisation and vaccine effectiveness for Omicron VOC-21NOV-01 (B.1.1.529) 31 December 2021 This briefing provides an update on previous briefings up to 23 December 2021 SARS-CoV-2 variants of concern and variants under investigation in England: Omicron update 2 Contents Summary............