1. COVID-19 due to the B.1.617.2 (Delta) variant compared to B.1.1.7 (Alpha) variant of SARS-CoV-2: a prospective observational cohort study
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Kläser, K., Molteni, E., Graham, M., Canas, L. S., Österdahl, M. F., Antonelli, M., Chen, L., Deng, J., Murray, B., Kerfoot, E., Wolf, J., May, A., Fox, B., Capdevila, J., Aanensen, D. M., Abudahab, K., Adams, H., Adams, A., Afifi, S., Aggarwal, D., Ahmad, S. S. Y., Aigrain, L., Alcolea-Medina, A., Alikhan, N-F, Allara, E., Amato, R., Angyal, A., Annett, T., Aplin, S., Ariani, C. V., Asad, H., Ash, A., Ashfield, P., Ashford, F., Atkinson, L., Attwood, S. W., Auckland, C., Aydin, A., Baker, D. J., Baker, P., Balcazar, C. E., Ball, J., Barrett, J. C., Barrow, M., Barton, E., Bashton, M., Bassett, A. R., Batra, R., Baxter, C., Bayzid, N., Beaver, C., Beckett, A. H., Beckwith, S. M., Bedford, L., Beer, R., Beggs, A., Bellis, K. L., Berry, L., Bertolusso, B., Best, A., Betteridge, E., Bibby, D., Bicknell, K., Binns, D., Birchley, A., Bird, P. W., Bishop, C., Blacow, R., Blakey, V., Blane, B., Bolt, F., Bonfield, J., Bonner, S., Bonsall, D., Boswell, T., Bosworth, A., Bourgeois, Y., Boyd, O., Bradley, D. T., Breen, C., Bresner, C., Breuer, J., Bridgett, S., Bronner, I. F., Brooks, E., Broos, A., Brown, J. R., Bucca, G., Buchan, S. L., Buck, D., Bull, M., Burns, P. J., Burton-Fanning, S., Byaruhanga, T., Byott, M., Campbell, S., Carabelli, A. M., Cargill, J. S., Carlile, M., Carvalho, S. F., Casey, A., Castigador, A., Catalan, J., Chalker, V., Chaloner, N. J., Chand, M., Chappell, J. G., Charalampous, T., Chatterton, W., Chaudhry, Y., Churcher, C. M., Clark, G., Clarke, P., Cogger, B. J., Cole, K., Collins, J., Colquhoun, R., Connor, T. R., Cook, K. F., Coombes, J., Corden, S., Cormie, C., Cortes, N., Cotic, M., Cotton, S., Cottrell, S., Coupland, L., Cox, M. G., Cox, A., Craine, N., Crawford, L., Cross, A., Crown, M. R., Crudgington, D., Cumley, N., Curran, T., Curran, M. D., da Silva Filipe, A., Dabrera, G., Darby, A. C., Davidson, R. K., Davies, A., Davies, R. M., Davis, T., de Angelis, D., De Lacy, E., de Oliveira Martins, L., de Silva, T. I., Debebe, J., Denton-Smith, R., Dervisevic, S., Dewar, R., Dey, J., Dias, J., Dobie, D., Dorman, M. J., Downing, F., Driscoll, M., du Plessis, L., Duckworth, N., Durham, J., Eastick, K., Easton, L. J., Eccles, R., Edgeworth, J., Edwards, S., Bouzidi, K. E., Eldirdiri, S., Ellaby, N., Elliott, S., Eltringham, G., Ensell, L., Erkiert, M. J., Zamudio, M. E., Essex, S., Evans, J. M., Evans, C., Everson, W., Fairley, D. J., Fallon, K., Fanaie, A., Farr, B. W., Fearn, C., Feltwell, T., Ferguson, L., Fina, L., Flaviani, F., Fleming, V. M., Forrest, S., Foster-Nyarko, E., Foulkes, B. H., Foulser, L., Fragakis, M., Frampton, D., Francois, S., Fraser, C., Freeman, T. M., Fryer, H., Fuchs, M., Fuller, W., Gajee, K., Galai, K., Gallagher, A., Gallagher, E., Gallagher, M. D., Gallis, M., Gaskin, A., Gatica-Wilcox, B., Geidelberg, L., Gemmell, M., Georgana, I., George, R. P., Gifford, L., Gilbert, L., Girgis, S. T., Glaysher, S., Goldstein, E. J., Golubchik, T., Gomes, A. N., Gonçalves, S., Goodfellow, I. G., Goodwin, S., Goudarzi, S., Gourtovaia, M., Graham, C. A., Graham, L., Grant, P. R., Green, L. R., Green, A., Greenaway, J., Gregory, R., Guest, M., Gunson, R. N., Gupta, R. K., Gutierrez, B., Haldenby, S. T., Hamilton, W. L., Hansford, S. E., Haque, T., Harris, K. A., Harrison, I., Harrison, E. M., Hart, J., Hartley, .J. A., Harvey, W. T., Harvey, M., Hassan-Ibrahim, M. O., Heaney, J., Helmer, T., Henderson, J. H., Hesketh, A. R., Hey, J., Heyburn, D., Higginson, E. E., Hill, V., Hill, J. D., Hilson, R. A., Hilvers, E., Holden, M. T. G., Hollis, A., Holmes, C. W., Holmes, N., Holmes, A. H., Hopes, R., Hornsby, H. R., Hosmillo, M., Houlihan, C., Howson-Wells, H. C., Hsu, S. N., Hubb, J., Huckson, H., Hughes, W., Hughes, J., Hughes, M., Hutchings, S., Idle, G, Illingworth, CJ, Impey, R, Irish-Tavares, D, Iturriza-Gomara, M, Izuagbe, R, Jackson, C, Jackson, B, Jackson, LM, Jackson, KA, Jackson, DK, Jahun, AS, James, V, James, K, Jeanes, C, Jeffries, AR, Jeremiah, S, Jermy, A, John, M, Johnson, R, Johnson, K, Johnston, I, Jones, O, Jones, S, Jones, H, Jones, CR, Jones, N, Joseph, A, Judges, S, Kay, GL, Kay, S, Keatley, J - P, Keeley, AJ, Kenyon, A, Kermack, LM, Khakh, M, Kidd, SP, Kimuli, M, Kirk, S, Kitchen, C, Kitchman, K, Knight, BA, Koshy, C, Kraemer, MUG, Kumziene-Summerhayes, S, Kwiatkowski, D, Lackenby, A, Laing, KG, Lampejo, T, Langford, CF, Lavin, D, Lawton, AI, Lee, JCD, Lee, D, Lensing, SV, Leonard, S, Levett, LJ, Le-Viet, T, Lewis, J, Lewis, K, Liddle, J, Liggett, S, Lillie, PJ, Lindsey, BB, Lister, MM, Livett, R, Lo, S, Loman, NJ, Loose, MW, Louka, SF, Loveson, KF, Lowdon, S, Lowe, H, Lowe, HL, Lucaci, AO, Ludden, C, Lynch, J, Lyons, RA, Lythgoe, K, Machin, NW, MacIntyre-Cockett, G, Mack, A, Macklin, B, Maclean, A, Macnaughton, E, Madona, P, Maes, M, Maftei, L, Mahanama, AIK, Mahungu, TW, Mair, D, Maksimovic, J, Malone, CS, Maloney, D, Manesis, N, Manley, R, Mantzouratou, A, Marchbank, A, Mariappan, A, Martincorena, I, Nunez, RTM, Mather, AE, Maxwell, P, Mayhew, M, Mbisa, T, McCann, CM, McCarthy, SA, McCluggage, K, McClure, PC, McCrone, JT, McHugh, MP, McKenna, JP, McKerr, C, McManus, GM, McMurray, CL, McMurray, C, McNally, A, Meadows, L, Medd, N, Megram, O, Menegazzo, M, Merrick, I, Michell, SL, Michelsen, ML, Mirfenderesky, M, Mirza, J, Miskelly, J, Moles-Garcia, E, Moll, RJ, Molnar, Z, Monahan, IM, Mondani, M, Mookerjee, S, Moore, C, Moore, J, Moore, N, Morcrette, H, Morgan, S, Morgan, M, Mori, M, Morriss, A, Moses, S, Mower, C, Muir, P, Mukaddas, A, Munemo, F, Munn, R, Murray, A, Murray, LJ, Murray, DR, Mutingwende, M, Myers, R, Nastouli, E, Nebbia, G, Nelson, A, Nelson, C, Nicholls, S, Nichols, J, Nicodemi, R, Nomikou, K, O’Grady, J, O’Brien, S, Odedra, M, Ohemeng-Kumi, N, Oliver, K, Orton, RJ, Osman, H, O’Toole, Á, Pacchiarini, N, Padgett, D, Page, AJ, Park, EJ, Park, NR, Parker, MD, Parmar, S, Partridge, DG, Pascall, D, Patel, A, Patel, B, Paterson, S, Payne, BAI, Peacock, SJ, Pearson, C, Pelosi, E, Percival, B, Perkins, J, Perry, M, Pinckert, ML, Platt, S, Podplomyk, O, Pohare, M, Pond, M, Pope, CF, Poplawski, R, Powell, J, Poyner, J, Prestwood, L, Price, A, Price, JR, Prieto, JA, Pritchard, DT, Prosolek, SJ, Pugh, G, Pusok, M, Pybus, OG, Pymont, HM, Quail, MA, Quick, J, Radulescu, C, Raghwani, J, Ragonnet-Cronin, M, Rainbow, L, Rajan, D, Rajatileka, S, Ramadan, NA, Rambaut, A, Ramble, J, Randell, PA, Randell, P, Ratcliffe, L, Raviprakash, V, Raza, M, Redshaw, NM, Rey, S, Reynolds, N, Richter, A, Robertson, DL, Robinson, E, Robson, SC, Rogan, F, Rooke, S, Rowe, W, Roy, S, Rudder, S, Ruis, C, Rushton, S, Ryan, F, Saeed, K, Samaraweera, B, Sambles, CM, Sanderson, R, Sanderson, T, Sang, F, Sass, T, Scher, E, Scott, G, Scott, C, Sehmi, J, Shaaban, S, Shah, D, Shaw, J, Shelest, E, Shepherd, JG, Sheridan, LA, Sheriff, N, Shirley, L, Sillitoe, J, Silviera, S, Simpson, DA, Singh, A, Singleton, D, Skvortsov, T, Sloan, TJ, Sluga, G, Smith, K, Smith, KS, Smith, P, Smith, DL, Smith, L, Smith, CP, Smith, N, Smollett, KL, Snell, LB, Somassa, T, Southgate, J, Spellman, K, Chapman, MHS, Spurgin, LG, Spyer, MJ, Stanley, R, Stanley, W, Stanton, TD, Starinskij, I, Stockton, J, Stonehouse, S, Storey, N, Studholme, DJ, Sudhanva, M, Swindells, E, Taha, Y, Tan, NK, Tang, JW, Tang, M, Taylor, BEW, Taylor, JF, Taylor, S, Temperton, B, Templeton, KE, Thomas, C, Thomson, L, Thomson, EC, Thornton, A, Thurston, SAJ, Todd, JA, Tomb, R, Tong, L, Tonkin-Hill, G, Torok, ME, Tovar-Corona, JM, Trebes, A, Trotter, AJ, Tsatsani, I, Turnbull, R, Turtle, L, Twohig, KA, Umpleby, H, Underwood, AP, Vamos, EE, Vasylyeva, TI, Vattipally, S, Vernet, G, Vipond, BB, Volz, EM, Walsh, S, Wang, D, Warne, B, Warwick-Dugdale, J, Wastnedge, E, Watkins, J, Watson, LK, Waugh, S, Webster, HJ, Weldon, D, Westwick, E, Whalley, T, Wheeler, H, Whitehead, M, Whiteley, M, Whitwham, A, Wierzbicki, C, Willford, NJ, Williams, L-A, Williams, R, Williams, C, Williams, CA, Williams, RJ, Williams, T, Williamson, KA, Wilson-Davies, E, Witele, E, Withell, KT, Witney, AA, Wolverson, P, Wong, N, Workman, T, Wright, V, Wright, DW, Wyatt, T, Wyllie, S, Xu-McCrae, L., Yavus, M., Yaze, G., Yeats, C. A., Yebra, G., Yew, W. C., Young, G. R., Young, J., Zarebski, A. E., Zhang, P., Modat, M., Hammers, A., Spector, T. D., Steves, C. J., Sudre, C. H., Ourselin, S., Duncan, E. L., Kläser, K., Molteni, E., Graham, M., Canas, L. S., Österdahl, M. F., Antonelli, M., Chen, L., Deng, J., Murray, B., Kerfoot, E., Wolf, J., May, A., Fox, B., Capdevila, J., Aanensen, D. M., Abudahab, K., Adams, H., Adams, A., Afifi, S., Aggarwal, D., Ahmad, S. S. Y., Aigrain, L., Alcolea-Medina, A., Alikhan, N-F, Allara, E., Amato, R., Angyal, A., Annett, T., Aplin, S., Ariani, C. V., Asad, H., Ash, A., Ashfield, P., Ashford, F., Atkinson, L., Attwood, S. W., Auckland, C., Aydin, A., Baker, D. J., Baker, P., Balcazar, C. E., Ball, J., Barrett, J. C., Barrow, M., Barton, E., Bashton, M., Bassett, A. R., Batra, R., Baxter, C., Bayzid, N., Beaver, C., Beckett, A. H., Beckwith, S. M., Bedford, L., Beer, R., Beggs, A., Bellis, K. L., Berry, L., Bertolusso, B., Best, A., Betteridge, E., Bibby, D., Bicknell, K., Binns, D., Birchley, A., Bird, P. W., Bishop, C., Blacow, R., Blakey, V., Blane, B., Bolt, F., Bonfield, J., Bonner, S., Bonsall, D., Boswell, T., Bosworth, A., Bourgeois, Y., Boyd, O., Bradley, D. T., Breen, C., Bresner, C., Breuer, J., Bridgett, S., Bronner, I. F., Brooks, E., Broos, A., Brown, J. R., Bucca, G., Buchan, S. L., Buck, D., Bull, M., Burns, P. J., Burton-Fanning, S., Byaruhanga, T., Byott, M., Campbell, S., Carabelli, A. M., Cargill, J. S., Carlile, M., Carvalho, S. F., Casey, A., Castigador, A., Catalan, J., Chalker, V., Chaloner, N. J., Chand, M., Chappell, J. G., Charalampous, T., Chatterton, W., Chaudhry, Y., Churcher, C. M., Clark, G., Clarke, P., Cogger, B. J., Cole, K., Collins, J., Colquhoun, R., Connor, T. R., Cook, K. F., Coombes, J., Corden, S., Cormie, C., Cortes, N., Cotic, M., Cotton, S., Cottrell, S., Coupland, L., Cox, M. G., Cox, A., Craine, N., Crawford, L., Cross, A., Crown, M. R., Crudgington, D., Cumley, N., Curran, T., Curran, M. D., da Silva Filipe, A., Dabrera, G., Darby, A. C., Davidson, R. K., Davies, A., Davies, R. M., Davis, T., de Angelis, D., De Lacy, E., de Oliveira Martins, L., de Silva, T. I., Debebe, J., Denton-Smith, R., Dervisevic, S., Dewar, R., Dey, J., Dias, J., Dobie, D., Dorman, M. J., Downing, F., Driscoll, M., du Plessis, L., Duckworth, N., Durham, J., Eastick, K., Easton, L. J., Eccles, R., Edgeworth, J., Edwards, S., Bouzidi, K. E., Eldirdiri, S., Ellaby, N., Elliott, S., Eltringham, G., Ensell, L., Erkiert, M. J., Zamudio, M. E., Essex, S., Evans, J. M., Evans, C., Everson, W., Fairley, D. J., Fallon, K., Fanaie, A., Farr, B. W., Fearn, C., Feltwell, T., Ferguson, L., Fina, L., Flaviani, F., Fleming, V. M., Forrest, S., Foster-Nyarko, E., Foulkes, B. H., Foulser, L., Fragakis, M., Frampton, D., Francois, S., Fraser, C., Freeman, T. M., Fryer, H., Fuchs, M., Fuller, W., Gajee, K., Galai, K., Gallagher, A., Gallagher, E., Gallagher, M. D., Gallis, M., Gaskin, A., Gatica-Wilcox, B., Geidelberg, L., Gemmell, M., Georgana, I., George, R. P., Gifford, L., Gilbert, L., Girgis, S. T., Glaysher, S., Goldstein, E. J., Golubchik, T., Gomes, A. N., Gonçalves, S., Goodfellow, I. G., Goodwin, S., Goudarzi, S., Gourtovaia, M., Graham, C. A., Graham, L., Grant, P. R., Green, L. R., Green, A., Greenaway, J., Gregory, R., Guest, M., Gunson, R. N., Gupta, R. K., Gutierrez, B., Haldenby, S. T., Hamilton, W. L., Hansford, S. E., Haque, T., Harris, K. A., Harrison, I., Harrison, E. M., Hart, J., Hartley, .J. A., Harvey, W. T., Harvey, M., Hassan-Ibrahim, M. O., Heaney, J., Helmer, T., Henderson, J. H., Hesketh, A. R., Hey, J., Heyburn, D., Higginson, E. E., Hill, V., Hill, J. D., Hilson, R. A., Hilvers, E., Holden, M. T. G., Hollis, A., Holmes, C. W., Holmes, N., Holmes, A. H., Hopes, R., Hornsby, H. R., Hosmillo, M., Houlihan, C., Howson-Wells, H. C., Hsu, S. N., Hubb, J., Huckson, H., Hughes, W., Hughes, J., Hughes, M., Hutchings, S., Idle, G, Illingworth, CJ, Impey, R, Irish-Tavares, D, Iturriza-Gomara, M, Izuagbe, R, Jackson, C, Jackson, B, Jackson, LM, Jackson, KA, Jackson, DK, Jahun, AS, James, V, James, K, Jeanes, C, Jeffries, AR, Jeremiah, S, Jermy, A, John, M, Johnson, R, Johnson, K, Johnston, I, Jones, O, Jones, S, Jones, H, Jones, CR, Jones, N, Joseph, A, Judges, S, Kay, GL, Kay, S, Keatley, J - P, Keeley, AJ, Kenyon, A, Kermack, LM, Khakh, M, Kidd, SP, Kimuli, M, Kirk, S, Kitchen, C, Kitchman, K, Knight, BA, Koshy, C, Kraemer, MUG, Kumziene-Summerhayes, S, Kwiatkowski, D, Lackenby, A, Laing, KG, Lampejo, T, Langford, CF, Lavin, D, Lawton, AI, Lee, JCD, Lee, D, Lensing, SV, Leonard, S, Levett, LJ, Le-Viet, T, Lewis, J, Lewis, K, Liddle, J, Liggett, S, Lillie, PJ, Lindsey, BB, Lister, MM, Livett, R, Lo, S, Loman, NJ, Loose, MW, Louka, SF, Loveson, KF, Lowdon, S, Lowe, H, Lowe, HL, Lucaci, AO, Ludden, C, Lynch, J, Lyons, RA, Lythgoe, K, Machin, NW, MacIntyre-Cockett, G, Mack, A, Macklin, B, Maclean, A, Macnaughton, E, Madona, P, Maes, M, Maftei, L, Mahanama, AIK, Mahungu, TW, Mair, D, Maksimovic, J, Malone, CS, Maloney, D, Manesis, N, Manley, R, Mantzouratou, A, Marchbank, A, Mariappan, A, Martincorena, I, Nunez, RTM, Mather, AE, Maxwell, P, Mayhew, M, Mbisa, T, McCann, CM, McCarthy, SA, McCluggage, K, McClure, PC, McCrone, JT, McHugh, MP, McKenna, JP, McKerr, C, McManus, GM, McMurray, CL, McMurray, C, McNally, A, Meadows, L, Medd, N, Megram, O, Menegazzo, M, Merrick, I, Michell, SL, Michelsen, ML, Mirfenderesky, M, Mirza, J, Miskelly, J, Moles-Garcia, E, Moll, RJ, Molnar, Z, Monahan, IM, Mondani, M, Mookerjee, S, Moore, C, Moore, J, Moore, N, Morcrette, H, Morgan, S, Morgan, M, Mori, M, Morriss, A, Moses, S, Mower, C, Muir, P, Mukaddas, A, Munemo, F, Munn, R, Murray, A, Murray, LJ, Murray, DR, Mutingwende, M, Myers, R, Nastouli, E, Nebbia, G, Nelson, A, Nelson, C, Nicholls, S, Nichols, J, Nicodemi, R, Nomikou, K, O’Grady, J, O’Brien, S, Odedra, M, Ohemeng-Kumi, N, Oliver, K, Orton, RJ, Osman, H, O’Toole, Á, Pacchiarini, N, Padgett, D, Page, AJ, Park, EJ, Park, NR, Parker, MD, Parmar, S, Partridge, DG, Pascall, D, Patel, A, Patel, B, Paterson, S, Payne, BAI, Peacock, SJ, Pearson, C, Pelosi, E, Percival, B, Perkins, J, Perry, M, Pinckert, ML, Platt, S, Podplomyk, O, Pohare, M, Pond, M, Pope, CF, Poplawski, R, Powell, J, Poyner, J, Prestwood, L, Price, A, Price, JR, Prieto, JA, Pritchard, DT, Prosolek, SJ, Pugh, G, Pusok, M, Pybus, OG, Pymont, HM, Quail, MA, Quick, J, Radulescu, C, Raghwani, J, Ragonnet-Cronin, M, Rainbow, L, Rajan, D, Rajatileka, S, Ramadan, NA, Rambaut, A, Ramble, J, Randell, PA, Randell, P, Ratcliffe, L, Raviprakash, V, Raza, M, Redshaw, NM, Rey, S, Reynolds, N, Richter, A, Robertson, DL, Robinson, E, Robson, SC, Rogan, F, Rooke, S, Rowe, W, Roy, S, Rudder, S, Ruis, C, Rushton, S, Ryan, F, Saeed, K, Samaraweera, B, Sambles, CM, Sanderson, R, Sanderson, T, Sang, F, Sass, T, Scher, E, Scott, G, Scott, C, Sehmi, J, Shaaban, S, Shah, D, Shaw, J, Shelest, E, Shepherd, JG, Sheridan, LA, Sheriff, N, Shirley, L, Sillitoe, J, Silviera, S, Simpson, DA, Singh, A, Singleton, D, Skvortsov, T, Sloan, TJ, Sluga, G, Smith, K, Smith, KS, Smith, P, Smith, DL, Smith, L, Smith, CP, Smith, N, Smollett, KL, Snell, LB, Somassa, T, Southgate, J, Spellman, K, Chapman, MHS, Spurgin, LG, Spyer, MJ, Stanley, R, Stanley, W, Stanton, TD, Starinskij, I, Stockton, J, Stonehouse, S, Storey, N, Studholme, DJ, Sudhanva, M, Swindells, E, Taha, Y, Tan, NK, Tang, JW, Tang, M, Taylor, BEW, Taylor, JF, Taylor, S, Temperton, B, Templeton, KE, Thomas, C, Thomson, L, Thomson, EC, Thornton, A, Thurston, SAJ, Todd, JA, Tomb, R, Tong, L, Tonkin-Hill, G, Torok, ME, Tovar-Corona, JM, Trebes, A, Trotter, AJ, Tsatsani, I, Turnbull, R, Turtle, L, Twohig, KA, Umpleby, H, Underwood, AP, Vamos, EE, Vasylyeva, TI, Vattipally, S, Vernet, G, Vipond, BB, Volz, EM, Walsh, S, Wang, D, Warne, B, Warwick-Dugdale, J, Wastnedge, E, Watkins, J, Watson, LK, Waugh, S, Webster, HJ, Weldon, D, Westwick, E, Whalley, T, Wheeler, H, Whitehead, M, Whiteley, M, Whitwham, A, Wierzbicki, C, Willford, NJ, Williams, L-A, Williams, R, Williams, C, Williams, CA, Williams, RJ, Williams, T, Williamson, KA, Wilson-Davies, E, Witele, E, Withell, KT, Witney, AA, Wolverson, P, Wong, N, Workman, T, Wright, V, Wright, DW, Wyatt, T, Wyllie, S, Xu-McCrae, L., Yavus, M., Yaze, G., Yeats, C. A., Yebra, G., Yew, W. C., Young, G. R., Young, J., Zarebski, A. E., Zhang, P., Modat, M., Hammers, A., Spector, T. D., Steves, C. J., Sudre, C. H., Ourselin, S., and Duncan, E. L.
- Abstract
The Delta (B.1.617.2) variant was the predominant UK circulating SARS-CoV-2 strain between May and December 2021. How Delta infection compares with previous variants is unknown. This prospective observational cohort study assessed symptomatic adults participating in the app-based COVID Symptom Study who tested positive for SARS-CoV-2 from May 26 to July 1, 2021 (Delta overwhelmingly the predominant circulating UK variant), compared (1:1, age- and sex-matched) with individuals presenting from December 28, 2020 to May 6, 2021 (Alpha (B.1.1.7) the predominant variant). We assessed illness (symptoms, duration, presentation to hospital) during Alpha- and Delta-predominant timeframes; and transmission, reinfection, and vaccine effectiveness during the Delta-predominant period. 3581 individuals (aged 18 to 100 years) from each timeframe were assessed. The seven most frequent symptoms were common to both variants. Within the first 28 days of illness, some symptoms were more common with Delta versus Alpha infection (including fever, sore throat, and headache) and some vice versa (dyspnoea). Symptom burden in the first week was higher with Delta versus Alpha infection; however, the odds of any given symptom lasting ≥ 7 days was either lower or unchanged. Illness duration ≥ 28 days was lower with Delta versus Alpha infection, though unchanged in unvaccinated individuals. Hospitalisation for COVID-19 was unchanged. The Delta variant appeared more (1.49) transmissible than Alpha. Re-infections were low in all UK regions. Vaccination markedly reduced the risk of Delta infection (by 69-84%). We conclude that COVID-19 from Delta or Alpha infections is similar. The Delta variant is more transmissible than Alpha; however, current vaccines showed good efficacy against disease. This research framework can be useful for future comparisons with new emerging variants. © 2022, The Author(s).