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

Kläser, Kerstin, Molteni, Erika, Graham, Mark, Canas, Liane S., Österdahl, Marc F., Antonelli, Michela, Chen, Liyuan, Deng, Jie, Murray, Benjamin, Kerfoot, Eric, Wolf, Jonathan, May, Anna, Fox, Ben, Capdevila, Joan, Modat, Marc, Hammers, Alexander, Spector, Tim D., Steves, Claire J., Sudre, Carole H., Ourselin, Sebastien and Duncan, Emma L. and COVID-19 Genomics U. K. (COG-UK) Consortium (2022) 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. Scientific Reports, 12 (1). ISSN 2045-2322

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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.

Item Type: Article
Additional Information: Funding: UK Government Department of Health and Social Care, Wellcome Trust, UK Engineering and Physical Sciences Research Council, UK Research and Innovation London Medical Imaging & Artificial Intelligence Centre for Value Based Healthcare, UK National Institute for Health Research, UK Medical Research Council, British Heart Foundation, Alzheimer’s Society, and ZOE Limited.
Uncontrolled Keywords: general,sdg 3 - good health and well-being ,/dk/atira/pure/subjectarea/asjc/1000
Faculty \ School: Faculty of Medicine and Health Sciences > Norwich Medical School
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Depositing User: LivePure Connector
Date Deposited: 14 Jul 2022 10:30
Last Modified: 21 Apr 2023 02:33
DOI: 10.1038/s41598-022-14016-0

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