Hospital admission and emergency care attendance risk for SARS-CoV-2 delta (B.1.617.2) compared with alpha (B.1.1.7) variants of concern: a cohort study

Twohig, Katherine A., Nyberg, Tommy, Zaidi, Asad, Thelwall, Simon, Sinnathamby, Mary A., Aliabadi, Shirin, Seaman, Shaun R., Harris, Ross J., Hope, Russell, Lopez-Bernal, Jamie, Gallagher, Eileen, Charlett, Andre, De Angelis, Daniela, Presanis, Anne M. and Dabrera, Gavin and COVID-19 Genomics UK (COG-UK) Consortium (2022) Hospital admission and emergency care attendance risk for SARS-CoV-2 delta (B.1.617.2) compared with alpha (B.1.1.7) variants of concern: a cohort study. The Lancet Infectious Diseases, 22 (1). pp. 35-42. ISSN 1473-3099

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Abstract

Background: The SARS-CoV-2 delta (B.1.617.2) variant was first detected in England in March, 2021. It has since rapidly become the predominant lineage, owing to high transmissibility. It is suspected that the delta variant is associated with more severe disease than the previously dominant alpha (B.1.1.7) variant. We aimed to characterise the severity of the delta variant compared with the alpha variant by determining the relative risk of hospital attendance outcomes. Methods: This cohort study was done among all patients with COVID-19 in England between March 29 and May 23, 2021, who were identified as being infected with either the alpha or delta SARS-CoV-2 variant through whole-genome sequencing. Individual-level data on these patients were linked to routine health-care datasets on vaccination, emergency care attendance, hospital admission, and mortality (data from Public Health England's Second Generation Surveillance System and COVID-19-associated deaths dataset; the National Immunisation Management System; and NHS Digital Secondary Uses Services and Emergency Care Data Set). The risk for hospital admission and emergency care attendance were compared between patients with sequencing-confirmed delta and alpha variants for the whole cohort and by vaccination status subgroups. Stratified Cox regression was used to adjust for age, sex, ethnicity, deprivation, recent international travel, area of residence, calendar week, and vaccination status. Findings: Individual-level data on 43 338 COVID-19-positive patients (8682 with the delta variant, 34 656 with the alpha variant; median age 31 years [IQR 17–43]) were included in our analysis. 196 (2·3%) patients with the delta variant versus 764 (2·2%) patients with the alpha variant were admitted to hospital within 14 days after the specimen was taken (adjusted hazard ratio [HR] 2·26 [95% CI 1·32–3·89]). 498 (5·7%) patients with the delta variant versus 1448 (4·2%) patients with the alpha variant were admitted to hospital or attended emergency care within 14 days (adjusted HR 1·45 [1·08–1·95]). Most patients were unvaccinated (32 078 [74·0%] across both groups). The HRs for vaccinated patients with the delta variant versus the alpha variant (adjusted HR for hospital admission 1·94 [95% CI 0·47–8·05] and for hospital admission or emergency care attendance 1·58 [0·69–3·61]) were similar to the HRs for unvaccinated patients (2·32 [1·29–4·16] and 1·43 [1·04–1·97]; p=0·82 for both) but the precision for the vaccinated subgroup was low. Interpretation: This large national study found a higher hospital admission or emergency care attendance risk for patients with COVID-19 infected with the delta variant compared with the alpha variant. Results suggest that outbreaks of the delta variant in unvaccinated populations might lead to a greater burden on health-care services than the alpha variant. Funding: Medical Research Council; UK Research and Innovation; Department of Health and Social Care; and National Institute for Health Research.

Item Type: Article
Additional Information: Funding Information: We acknowledge the national collaborative effort undertaken by the institutions participating in the COVID-19 Genomics UK (COG-UK) consortium that enables this national public health response. We thank the Hospital-onset COVID Team (Simon Collin and Efejiro Ashano) and NHS-Digital. We thank Lara Utsi for assisting with the linkage to the vaccination dataset. We thank Natalie Groves for work on the variant case definitions and supporting the genome classification process. We acknowledge the Public Health England DataLake, DataStore, and Second Generation Surveillance System teams for maintenance of the databases in which data are stored. This research was funded by the Medical Research Council (MRC; authors DDA and AMP: Unit Programme number MC_UU_00002/11; author SRS: Unit Programme number MC_UU_00002/10); and via a grant from the MRC UK Research and Innovation (UKRI)/Department of Health and Social Care National Institute for Health Research (NIHR) COVID-19 rapid response call (authors TN, AC, DDA, and AMP: grant reference MC_PC_19074). The COG-UK consortium is supported by funding from the MRC part of UKRI, the NIHR and Genome Research Limited, operating as the Wellcome Sanger Institute.
Uncontrolled Keywords: infectious diseases,sdg 3 - good health and well-being ,/dk/atira/pure/subjectarea/asjc/2700/2725
Faculty \ School: Faculty of Science
Faculty of Medicine and Health Sciences > Norwich Medical School
Faculty of Social Sciences > School of Global Development (formerly School of International Development)
Faculty of Science > School of Biological Sciences

Faculty of Science > School of Environmental Sciences
Faculty of Social Sciences > Norwich Business School
University of East Anglia Research Groups/Centres > Faculty of Arts and Humanities > Research Centres > Sainsbury Centre for the Visual Arts
Faculty of Science > School of Pharmacy (former - to 2024)

Faculty of Science > School of Computing Sciences

Faculty of Medicine and Health Sciences > School of Health Sciences
UEA Research Groups: Faculty of Science > Research Groups > Interactive Graphics and Audio
Faculty of Medicine and Health Sciences > Research Groups > Nutrition and Preventive Medicine
Faculty of Medicine and Health Sciences > Research Centres > Norwich Institute for Healthy Aging
Faculty of Medicine and Health Sciences > Research Centres > Lifespan Health
Faculty of Medicine and Health Sciences > Research Groups > Musculoskeletal Medicine
Faculty of Medicine and Health Sciences > Research Centres > Metabolic Health
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Depositing User: LivePure Connector
Date Deposited: 14 Jul 2022 00:23
Last Modified: 25 Sep 2024 16:27
URI: https://ueaeprints.uea.ac.uk/id/eprint/86101
DOI: 10.1016/S1473-3099(21)00475-8

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