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 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) varia...

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Published in:	The Lancet infectious diseases Vol. 22; no. 1; pp. 35 - 42
Main Authors:	Aliabadi, Shirin, Lopez-Bernal, Jamie, Moore, Nathan, Golubchik, Tanya, Cogger, Benjamin, Wantoch, Michelle, Spellman, Karla, McCluggage, Kathryn, Munn, Robert, Fuller, William, Charalampous, Themoula, Robson, Samuel, Abudahab, Khalil, Willingham, Iona, Raviprakash, Veena, Loose, Matthew, Coll, Francesc, Wilson, Harry, Pybus, Oliver, Zarebski, Alex, Jahun, Aminu, Fisher, Chloe, Siveroni, Igor, Boyd, Olivia, Smollett, Katherine, Poplawski, Radoslaw, Sluga, Graciela, Nichols, Jenna, Johnson, Natasha, Singer, Joshua, Nickbakhsh, Seema, Carden, Holli, Taha, Yusri, Blacow, Rachel, McHugh, Martin, Stanley, Rachael, Meader, Emma, Coupland, Lindsay, Peto, Timothy, Sloan, Tim, Chauhan, Anoop, Pearson, Clare, Robinson, Esther, Muir, Peter, Pymont, Hannah, Hutchings, Stephanie, Bibby, David, Lee, David, Ellaby, Nicholas, Manesis, Nikos, Bishop, Chloe, Gaskin, Amy, Gatica-Wilcox, Bree, Cronin, Michelle, Cottrell, Simon, Edwards, Sue, Aydin, Alp, Ratcliffe, Liz, Acheson, Erwan, Ellard, Sian, Irish-Tavares, Dianne, Hart, Jennifer, Symmonds, Amanda, Bourgeois, Yann, Dent, Hannah, Paul, Hannah, Partridge, David, Bonner, Stephen, Silveira, Siona, Williams, Charlotte, Jeremiah, Sarah, Berry, Lisa, Jones, Katie, Percival, Benita, Hesketh, Andrew, Girgis, Sophia, Forrest, Sally, Gupta, Ravi, Ludden, Catherine, Bewshea, Claire, Temperton, Ben, Warwick-Dugdale, Joanna, Studholme, David, Jeffries, Aaron, Jackson, Kathryn, Gregory, Richard, Wierzbicki, Claudia, Green, Luke, Freeman, Timothy, Cerda, Alberto, Alderton, Alex, Amato, Roberto, Ariani, Cristina, Beale, Mathew, Bellis, Katherine, Kwiatkowski, Dominic, McGuigan, Samantha, Prestwood, Liam, Spencer Chapman, Michael, Tonkin-Hill, Gerry
Format:	Journal Article
Language:	English
Published:	United States Elsevier Ltd 01-01-2022 Elsevier Limited Elsevier Science ;, The Lancet Pub. Group
Subjects:	Adolescent Adult Aged Aged, 80 and over Child Child, Preschool Cohort analysis Cohort Studies Coronaviruses COVID-19 COVID-19 - epidemiology COVID-19 - virology COVID-19 vaccines Datasets Deprivation Emergency medical care Emergency medical services Emergency Medical Services - statistics & numerical data England - epidemiology Female Gene sequencing Genomes Health care Health services Health surveillance Hospitalization Hospitalization - statistics & numerical data Humans Immunization Infections Infectious diseases Laboratories Male Medical research Middle Aged Mortality Patient admissions Patients Proportional Hazards Models Public health Risk SARS-CoV-2 - classification SARS-CoV-2 - pathogenicity Severe acute respiratory syndrome coronavirus 2 Severity of Illness Index Subgroups Vaccination Vaccines Viral diseases Whole genome sequencing Young Adult England Scotland United Kingdom > UK India
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Summary:	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. 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. 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. 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. Medical Research Council; UK Research and Innovation; Department of Health and Social Care; and National Institute for Health Research.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 Contributed equally. Full list of consortium names and affiliations are in appendix pp 11–17
ISSN:	1473-3099 1474-4457 1474-4457
DOI:	10.1016/S1473-3099(21)00475-8