- 18 August 2022
- Journal article
Inconsistent directions of change in case severity across successive SARS-CoV-2 variant waves suggests an unpredictable future
Objective To determine how the severity of successively dominant SARS-CoV-2 variants changed over the course of the COVID-19 pandemic.
Design Retrospective cohort analysis.
Setting Community- and hospital-sequenced COVID-19 cases in the NHS Greater Glasgow and Clyde (NHS GG&C) Health Board.
Participants All sequenced non-nosocomial adult COVID-19 cases in NHS GG&C infected with the relevant SARS-CoV-2 lineages during analysis periods. B.1.177/Alpha: 1st November 2020 - 30th January 2021 (n = 1640). Alpha/Delta: 1st April - 30th June 2021 (n = 5552). AY.4.2 Delta/non-AY.4.2 Delta: 1st July - 31st October 2021 (n = 9613). Non-AY.4.2 Delta/Omicron: 1st - 31st December 2021 (n = 3858).
Main outcome measures Admission to hospital, ICU, or death within 28 days of positive COVID-19 test
Results For B.1.177/Alpha, 300 of 807 B.1.177 cases were recorded as hospitalised or worse, compared to 232 of 833 Alpha cases. After adjustment, the cumulative odds ratio was 1.51 (95% CI: 1.08-2.11) for Alpha versus B.1.177. For Alpha/Delta, 113 of 2104 Alpha cases were recorded as hospitalised or worse, compared to 230 of 3448 Delta cases. After adjustment, the cumulative odds ratio was 2.09 (95% CI: 1.42-3.08) for Delta versus Alpha. For non-AY.4.2 Delta/AY.4.2 Delta, 845 of 8644 non-AY.4.2 Delta cases were recorded as hospitalised or worse, compared to 101 of 969 AY.4.2 Delta cases. After adjustment, the cumulative odds ratio was 0.99 (95% CI: 0.76-1.27) for AY.4.2 Delta versus non-AY.4.2 Delta. For non-AY.4.2 Delta/Omicron, 30 of 1164 non-AY.4.2 Delta cases were recorded as hospitalised or worse, compared to 26 of 2694 Omicron cases. After adjustment, the median cumulative odds ratio was 0.49 (95% CI: 0.22-1.06) for Omicron versus non-AY.4.2 Delta.
Conclusions The direction of change in disease severity between successively emerging SARS-CoV-2 variants of concern was inconsistent. This heterogeneity demonstrates that severity associated with future SARS-CoV-2 variants is unpredictable.
The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY 4.0 International license. http://creativecommons.org/licenses/by/4.0/
Pascall, D., Vink, E., Blacow, R., Bulteel, N., Campbell, A., Campbell, R., Clifford, S., Davis, C., Da Silva Filipe, A., Sakka, N., Fjodorova, L., Forrest, R., Goldstein, E., Gunson, R., Haughney, J., Holden, M., Honour, P., Hughes, J., James, E., Lewis, T., MacLean, O., McHugh, M., Mollett, G., Nyberg, T., Onishi, Y., Parcell, B., Ray, S., Robertson, D., Seaman, S., Shabaan, S., Shepherd, J., Smollett, K., Templeton, K., Wastnedge, E., Wilkie, C., Williams, T., COVID-19 Genomics UK (COG-UK) consortium & Thomson, E. 2022, 'Inconsistent directions of change in case severity across successive SARS-CoV-2 variant waves suggests an unpredictable future'. To be published in medRxiv [Preprint]. Available at: https://doi.org/10.1101/2022.03.24.22272915