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

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Title

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

Description

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.

Date Last Updated (Year-Month-Day)

2021-08-27

Citation

Twohig, Katherine A., Tommy Nyberg, Asad Zaidi, Simon Thelwall, Mary A. Sinnathamby, Shirin Aliabadi, Shaun R. Seaman, Ross J. Harris, Russell Hope, Jamie Lopez-Bernal, Eileen Gallagher, Andre Charlett, Daniela De Angelis, Anne M. Presanis, Gavin Dabrera, Cherian Koshy, Amy Ash, Emma Wise, Nathan Moore, Matilde Mori, Nick Cortes, Jessica Lynch, Stephen Kidd, Derek Fairley, Tanya Curran, James McKenna, Helen Adams, Christophe Fraser, Tanya Golubchik, David Bonsall, Mohammed Hassan-Ibrahim, Cassandra Malone, Benjamin Cogger, Michelle Wantoch, Nicola Reynolds, Ben Warne, Joshua Maksimovic, Karla Spellman, Kathryn McCluggage, Michaela John, Robert Beer, Safiah Afifi, Sian Morgan, Angela Marchbank, Anna Price, Christine Kitchen, Huw Gulliver, Ian Merrick, Joel Southgate, Martyn Guest, Robert Munn, Trudy Workman, Thomas Connor, William Fuller, Catherine Bresner, Luke Snell, Amita Patel, Themoula Charalampous, Gaia Nebbia, Rahul Batra, Jonathan Edgeworth, Samuel Robson, Angela Beckett, David Aanensen, Anthony Underwood, Corin Yeats, Khalil Abudahab, Ben Taylor, Mirko Menegazzo, Gemma Clark, Wendy Smith, Manjinder Khakh, Vicki Fleming, Michelle Lister, Hannah Howson-Wells, Louise Berry, Tim Boswell, Amelia Joseph, Iona Willingham, Carl Jones, Christopher Holmes, Paul Bird, Thomas Helmer, Karlie Fallon, Julian Tang, Veena Raviprakash, Sharon Campbell, Nicola Sheriff, Victoria Blakey, Lesley-Anne Williams, Matthew Loose, Nadine Holmes, Christopher Moore, Matthew Carlile, Victoria Wright, Fei Sang, Johnny Debebe, Francesc Coll, Adrian Signell, Gilberto Betancor, Harry Wilson, Sahar Eldirdiri, Anita Kenyon, Thomas Davis, Oliver Pybus, Louis du Plessis, Alex Zarebski, Jayna Raghwani, Moritz Kraemer, Sarah Francois, Stephen Attwood, Tetyana Vasylyeva, Marina Escalera Zamudio, Bernardo Gutierrez, M. Estee Torok, William Hamilton, Ian Goodfellow, Grant Hall, Aminu Jahun, Yasmin Chaudhry, Myra Hosmillo, Malte Pinckert, Iliana Georgana, Samuel Moses, Hannah Lowe, Luke Bedford, Jonathan Moore, Susanne Stonehouse, Chloe Fisher, Ali Awan, John BoYes, Judith Breuer, Kathryn Harris, Julianne Brown, Divya Shah, Laura Atkinson, Jack Lee, Nathaniel Storey, Flavia Flaviani, Adela Alcolea-Medina, Rebecca Williams, Gabrielle Vernet, Michael Chapman, Lisa Levett, Judith Heaney, Wendy Chatterton, Monika Pusok, Li Xu-McCrae, Darren Smith, Matthew Bashton, Gregory Young, Alison Holmes, Paul Randell, Alison Cox, Pinglawathee Madona, Frances Bolt, James Price, Siddharth Mookerjee, Manon Ragonnet-Cronin, Fabricia F. Nascimento, David Jorgensen, Igor Siveroni, Rob Johnson, Olivia Boyd, Lily Geidelberg, Erik Volz, Aileen Rowan, Graham Taylor, Katherine Smollett, Nicholas Loman, Joshua Quick, Claire McMurray, Joanne Stockton, Sam Nicholls, Will Rowe, Radoslaw Poplawski, Alan McNally, Rocio Martinez Nunez, Jenifer Mason, Trevor Robinson, Elaine O'Toole, Joanne Watts, Cassie Breen, Angela Cowell, Graciela Sluga, Nicholas Machin, Shazaad Ahmad, Ryan George, Fenella Halstead, Venkat Sivaprakasam, Wendy Hogsden, Chris Illingworth, Chris Jackson, Emma Thomson, James Shepherd, Patawee Asamaphan, Marc Niebel, Kathy Li, Rajiv Shah, Natasha Jesudason, Lily Tong, Alice Broos, Daniel Mair, Jenna Nichols, Stephen Carmichael, Kyriaki Nomikou, Elihu Aranday-Cortes, Natasha Johnson, Igor Starinskij, Ana da Silva Filipe, David Robertson, Richard Orton, Joseph Hughes, Sreenu Vattipally, Joshua Singer, Seema Nickbakhsh, Antony Hale, Louissa Macfarlane-Smith, Katherine Harper, Holli Carden, Yusri Taha, Brendan Payne, Shirelle Burton-Fanning, Sheila Waugh, Jennifer Collins, Gary Eltringham, Steven Rushton, Sarah O'Brien, Amanda Bradley, Alasdair Maclean, Guy Mollett, Rachel Blacow, Kate Templeton, Martin McHugh, Rebecca Dewar, Elizabeth Wastenge, Samir Dervisevic, Rachael Stanley, Emma Meader, Lindsay Coupland, Louise Smith, Clive Graham, Edward Barton, Debra Padgett, Garren Scott, Emma Swindells, Jane Greenaway, Andrew Nelson, Clare McCann, Wen Yew, Monique Andersson, Timothy Peto, Anita Justice, David Eyre, Derrick Crook, Tim Sloan, Nichola Duckworth, Sarah Walsh, Anoop Chauhan, Sharon Glaysher, Kelly Bicknell, Sarah Wyllie, Scott Elliott, Allyson Lloyd, Robert Impey, Nick Levene, Lynn Monaghan, Declan Bradley, Tim Wyatt, Elias Allara, Clare Pearson, Husam Osman, Andrew Bosworth, Esther Robinson, Peter Muir, Ian Vipond, Richard Hopes, Hannah Pymont, Stephanie Hutchings, Martin Curran, Surendra Parmar, Angie Lackenby, Tamyo Mbisa, Steven Platt, Shahjahan Miah, David Bibby, Carmen Manso, Jonathan Hubb, Meera Chand, Gavin Dabrera, Mary Ramsay, Daniel Bradshaw, Alicia Thornton, Richard Myers, Ulf Schaefer, Natalie Groves, Eileen Gallagher, David Lee, David Williams, Nicholas Ellaby, Ian Harrison, Hassan Hartman, Nikos Manesis, Vineet Patel, Chloe Bishop, Vicki Chalker, Juan Ledesma, Katherine Twohig, Matthew Holden, Sharif Shaaban, Alec Birchley, Alexander Adams, Alisha Davies, Amy Gaskin, Amy Plimmer, Bree Gatica-Wilcox, Caoimhe McKerr, Catherine Moore, Chris Williams, David Heyburn, Elen De Lacy, Ember Hilvers, Fatima Downing, Giri Shankar, Hannah Jones, Hibo Asad, Jason Coombes, Joanne Watkins, Johnathan Evans, Laia Fina, Laura Gifford, Lauren Gilbert, Lee Graham, Malorie Perry, Mari Morgan, Matthew Bull, Michelle Cronin, Nicole Pacchiarini, Noel Craine, Rachel Jones, Robin Howe, Sally Corden, Sara Rey, Sara Kumziene-SummerhaYes, Sarah Taylor, Simon Cottrell, Sophie Jones, Sue Edwards, Justin O'Grady, Andrew Page, Alison Mather, David Baker, Steven Rudder, Alp Aydin, Gemma Kay, Alexander Trotter, Nabil-Fareed Alikhan, Leonardo de Oliveira Martins, Thanh Le-Viet, Lizzie Meadows, Anna Casey, Liz Ratcliffe, David Simpson, Zoltan Molnar, Thomas Thompson, Erwan Acheson, Jane Masoli, Bridget Knight, Sian Ellard, Cressida Auckland, Christopher Jones, Tabitha Mahungu, Dianne Irish-Tavares, Tanzina Haque, Jennifer Hart, Eric Witele, Melisa Fenton, Ashok Dadrah, Amanda Symmonds, Tranprit Saluja, Yann Bourgeois, Garry Scarlett, Katie Loveson, Salman Goudarzi, Christopher Fearn, Kate Cook, Hannah Dent, Hannah Paul, David Partridge, Mohammad Raza, Cariad Evans, Kate Johnson, Steven Liggett, Paul Baker, Stephen Bonner, Sarah Essex, Ronan Lyons, Kordo Saeed, Adhyana Mahanama, Buddhini Samaraweera, Siona Silveira, Emanuela Pelosi, Eleri Wilson-Davies, Rachel Williams, Mark Kristiansen, Sunando Roy, Charlotte Williams, Marius Cotic, Nadua Bayzid, Adam Westhorpe, John Hartley, Riaz Jannoo, Helen Lowe, Angeliki Karamani, Leah Ensell, Jacqui Prieto, Sarah Jeremiah, Dimitris Grammatopoulos, Sarojini Pandey, Lisa Berry, Katie Jones, Alex Richter, Andrew Beggs, Angus Best, Benita Percival, Jeremy Mirza, Oliver Megram, Megan Mayhew, Liam Crawford, Fiona Ashcroft, Emma Moles-Garcia, Nicola Cumley, Colin Smith, Giselda Bucca, Andrew Hesketh, Beth Blane, Sophia Girgis, Danielle Leek, Sushmita Sridhar, Sally Forrest, Claire Cormie, Harmeet Gill, Joana Dias, Ellen Higginson, Mailis Maes, Jamie Young, Leanne Kermack, Ravi Gupta, Catherine Ludden, Sharon Peacock, Sophie Palmer, Carol Churcher, Nazreen Hadjirin, Alessandro Carabelli, Ellena Brooks, Kim Smith, Katerina Galai, Georgina McManus, Chris Ruis, Rose Davidson, Andrew Rambaut, Thomas Williams, Carlos Balcazar, Michael Gallagher, Áine O'Toole, Stefan Rooke, Verity Hill, Kathleen Williamson, Thomas Stanton, Stephen Michell, Claire Bewshea, Ben Temperton, Michelle Michelsen, Joanna Warwick-Dugdale, Robin Manley, Audrey Farbos, James Harrison, Christine Sambles, David Studholme, Aaron Jeffries, Leigh Jackson, Alistair Darby, Julian Hiscox, Steve Paterson, Miren Iturriza-Gomara, Kathryn Jackson, Anita Lucaci, Edith Vamos, Margaret Hughes, Lucille Rainbow, Richard Eccles, Charlotte Nelson, Mark Whitehead, Lance Turtle, Sam Haldenby, Richard Gregory, Matthew Gemmell, Claudia Wierzbicki, Hermione Webster, Thushan de Silva, Nikki Smith, Adrienn Angyal, Benjamin Lindsey, Danielle Groves, Luke Green, Dennis Wang, Timothy Freeman, Matthew Parker, Alexander Keeley, Paul Parsons, Rachel Tucker, Rebecca Brown, Matthew Wyles, Max Whiteley, Peijun Zhang, Marta Gallis, Stavroula Louka, Chrystala Constantinidou, Meera Unnikrishnan, Sascha Ott, Jeffrey Cheng, Hannah Bridgewater, Lucy Frost, Grace Taylor-Joyce, Richard Stark, Laura Baxter, Mohammad Alam, Paul Brown, Dinesh Aggarwal, Alberto Cerda, Tammy Merrill, Rebekah Wilson, Patrick McClure, Joseph Chappell, Theocharis Tsoleridis, Jonathan Ball, David Buck, John Todd, Angie Green, Amy Trebes, George MacIntyre-Cockett, Mariateresa de Cesare, Alex Alderton, Roberto Amato, Cristina Ariani, Mathew Beale, Charlotte Beaver, Katherine Bellis, Emma Betteridge, James Bonfield, John Danesh, Matthew Dorman, Eleanor Drury, Ben Farr, Luke Foulser, Sonia Goncalves, Scott Goodwin, Marina Gourtovaia, Ewan Harrison, David Jackson, Dorota Jamrozy, Ian Johnston, Leanne Kane, Sally Kay, Jon-Paul Keatley, Dominic Kwiatkowski, Cordelia Langford, Mara Lawniczak, Laura Letchford, Rich Livett, Stephanie Lo, Inigo Martincorena, Samantha McGuigan, Rachel Nelson, Steve Palmer, Naomi Park, Minal Patel, Liam Prestwood, Christoph Puethe, Michael Quail, Shavanthi Rajatileka, Carol Scott, Lesley Shirley, John Sillitoe, Michael Spencer Chapman, Scott Thurston, Gerry Tonkin-Hill, Danni Weldon, Diana Rajan, Iraad Bronner, Louise Aigrain, Nicholas Redshaw, Stefanie Lensing, Robert Davies, Andrew Whitwham, Jennifier Liddle, Kevin Lewis, Jaime Tovar-Corona, Steven Leonard, Jillian Durham, Andrew Bassett, Shane McCarthy, Robin Moll, Keith James, Karen Oliver, Alex Makunin, Jeff Barrett, and Rory Gunson. 2021. "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.

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.

Accessibility

Free online on Lancet site.