Directions of change in intrinsic case severity across successive SARS-CoV-2 variant waves have been inconsistent

The COVID-19 Genomics UK (COG-UK) Consortium, David J Pascall, Elen Vink, Rachel Blacow, Naomi Bulteel, Alasdair Campbell, Robyn Campbell, Sarah Clifford, Chris Davis, Ana da Silva Filipe, Noha El Sakka, Ludmila Fjodorova, Ruth Forrest, Emily Goldstein, Rory Gunson, John Haughney, Matthew T G Holden, Patrick Honour, Joseph Hughes, Edward JamesTim Lewis, Oscar MacLean, Martin McHugh, Guy Mollett, Tommy Nyberg, Yusuke Onishi, Ben Parcell, Surajit Ray, David L Robertson, Shaun R Seaman, Sharif Shabaan, James G Shepherd, Katherine Smollett, Kate Templeton, Elizabeth Wastnedge, Craig Wilkie, Thomas Williams, Emma C Thomson, Matthew Bashton, Darren Smith, Andrew Nelson, Gregory R. Young

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OBJECTIVES: To determine how the intrinsic severity of successively dominant SARS-CoV-2 variants changed over the course of the pandemic.

METHODS: A retrospective cohort analysis in the NHS Greater Glasgow and Clyde (NHS GGC) Health Board. All sequenced non-nosocomial adult COVID-19 cases in NHS GGC with relevant SARS-CoV-2 lineages (B.1.177/Alpha, Alpha/Delta, AY.4.2 Delta/non-AY.4.2 Delta, non-AY.4.2 Delta/Omicron, and BA.1 Omicron/BA.2 Omicron) during analysis periods were included. Outcome measures were hospital admission, ICU admission, or death within 28 days of positive COVID-19 test. We report the cumulative odds ratio; the ratio of the odds that an individual experiences a severity event of a given level vs all lower severity levels for the resident and the replacement variant after adjustment.

RESULTS: After adjustment for covariates, the cumulative odds ratio was 1.51 (95% CI: 1.08-2.11) for Alpha versus B.1.177, 2.09 (95% CI: 1.42-3.08) for Delta versus Alpha, 0.99 (95% CI: 0.76-1.27) for AY.4.2 Delta versus non-AY.4.2 Delta, 0.49 (95% CI: 0.22-1.06) for Omicron versus non-AY.4.2 Delta, and 0.86 (95% CI: 0.68-1.09) for BA.2 Omicron versus BA.1 Omicron.

CONCLUSIONS: The direction of change in intrinsic severity between successively emerging SARS-CoV-2 variants was inconsistent, reminding us that the intrinsic severity of future SARS-CoV-2 variants remains uncertain.

Original languageEnglish
Pages (from-to)128-135
Number of pages8
JournalJournal of Infection
Issue number2
Early online date1 Jun 2023
Publication statusPublished - 1 Aug 2023

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