Dataset Information

Clinical severity of Omicron SARS-CoV-2 variant relative to Delta in British Columbia, Canada: A retrospective analysis of whole genome sequenced cases.

ABSTRACT:

Background

In late 2021, the Omicron SARS-CoV-2 variant emerged and rapidly replaced Delta as the dominant variant globally. The increased transmissibility of the variant led to surges in case rates as well as increases in hospitalizations, however, the true severity of the variant remained unclear. We aimed to provide robust estimates of Omicron severity relative to Delta.

Methods

This study was conducted using a retrospective cohort design with data from the British Columbia COVID-19 Cohort - a large provincial surveillance platform with linkage to administrative datasets. To capture the time of co-circulation with Omicron and Delta, December 2021 was chosen as the study period. We included individuals diagnosed with Omicron or Delta infection, as determined by whole genome sequencing (WGS). To assess the severity (hospitalization, ICU admission, length of stay), we conducted adjusted Cox proportional hazard models, weighted by inverse probability of treatment weights (IPTW), accounting for age, sex, underlying comorbidities, vaccination, sociodemographic status, and geographical variation.

Results

The cohort was composed of 13,128 individuals (7,729 Omicron and 5,399 Delta). There were 419 COVID-19 hospitalizations, with 118 (22%) among people diagnosed with Omicron (crude rate = 1.5% Omicron, 5.6% Delta). In multivariable IPTW analysis, Omicron was associated with a 50% lower risk of hospitalization compared to Delta (aHR = 0.50; 95%CI = 0·43-0.59), a 73% lower risk of ICU admission (aHR = 0.27; 95%CI = 0.19-0.38), and a 5 days shorter hospital stay on average (aß=-5.03; 95% CI=-8.01, -2.05).

Conclusions

Our analysis supports findings from other studies demonstrating lower risk of severe outcomes in Omicron-infected individuals relative to Delta.

SUBMITTER: Harrigan SP

PROVIDER: S-EPMC9452171 | biostudies-literature | 2022 Aug

REPOSITORIES: biostudies-literature

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Publications

Clinical Severity of Severe Acute Respiratory Syndrome Coronavirus 2 Omicron Variant Relative to Delta in British Columbia, Canada: A Retrospective Analysis of Whole-Genome Sequenced Cases.

Harrigan Sean P SP Wilton James J Chong Mei M Abdia Younathan Y Velasquez Garcia Hector H Rose Caren C Taylor Marsha M Mishra Sharmistha S Sander Beate B Hoang Linda L Tyson John J Krajden Mel M Prystajecky Natalie N Janjua Naveed Z NZ Sbihi Hind H

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 20230201 3

<h4>Background</h4>In late 2021, the Omicron severe acute respiratory syndrome coronavirus 2 variant emerged and rapidly replaced Delta as the dominant variant. The increased transmissibility of Omicron led to surges in case rates and hospitalizations; however, the true severity of the variant remained unclear. We aimed to provide robust estimates of Omicron severity relative to Delta.<h4>Methods</h4>This retrospective cohort study was conducted with data from the British Columbia COVID-19 Cohor ...[more]

PMID: 36041009

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