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Exponential growth, high prevalence of SARS-CoV-2, and vaccine effectiveness associated with the Delta variant

Exponential growth, high prevalence of SARS-CoV-2, and vaccine effectiveness associated with the Delta variant
Exponential growth, high prevalence of SARS-CoV-2, and vaccine effectiveness associated with the Delta variant

SARS-CoV-2 infections were rising during early summer 2021 in many countries associated with the Delta variant. We assessed RT-PCR swab-positivity in the REal-time Assessment of Community Transmission-1 (REACT-1) study in England. We observed sustained exponential growth with average doubling time (June July 2021) of 25 days driven by complete replacement of Alpha variant by Delta, and by high prevalence at younger less-vaccinated ages. Unvaccinated people were three times more likely than double-vaccinated people to test positive. However, after adjusting for age and other variables, vaccine effectiveness for double-vaccinated people was estimated at between ~50% and ~60% during this period in England. Increased social mixing in the presence of Delta had the potential to generate sustained growth in infections, even at high levels of vaccination

0036-8075
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Brown, Rebecca
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COVID-19 Genomics UK (COG-UK) Consortium11‡
Elliott, Paul
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Haw, David
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Partridge, David G
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Brown, Rebecca
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COVID-19 Genomics UK (COG-UK) Consortium11‡ (2021) Exponential growth, high prevalence of SARS-CoV-2, and vaccine effectiveness associated with the Delta variant. Science (New York, N.Y.), 374 (6574), [eabl9551]. (doi:10.1126/science.abl9551).

Record type: Article

Abstract

SARS-CoV-2 infections were rising during early summer 2021 in many countries associated with the Delta variant. We assessed RT-PCR swab-positivity in the REal-time Assessment of Community Transmission-1 (REACT-1) study in England. We observed sustained exponential growth with average doubling time (June July 2021) of 25 days driven by complete replacement of Alpha variant by Delta, and by high prevalence at younger less-vaccinated ages. Unvaccinated people were three times more likely than double-vaccinated people to test positive. However, after adjusting for age and other variables, vaccine effectiveness for double-vaccinated people was estimated at between ~50% and ~60% during this period in England. Increased social mixing in the presence of Delta had the potential to generate sustained growth in infections, even at high levels of vaccination

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More information

e-pub ahead of print date: 2 November 2021
Published date: 2 November 2021

Identifiers

Local EPrints ID: 452292
URI: http://eprints.soton.ac.uk/id/eprint/452292
ISSN: 0036-8075
PURE UUID: 89ea9693-8ba2-4dba-8202-c068f8b0b2c1
ORCID for Kordo Saeed: ORCID iD orcid.org/0000-0003-0123-0302
ORCID for Jacqui A Prieto: ORCID iD orcid.org/0000-0002-5524-6775
ORCID for James W Harrison: ORCID iD orcid.org/0000-0002-3643-0489
ORCID for David Williams: ORCID iD orcid.org/0000-0001-7361-0246
ORCID for Rebecca Brown: ORCID iD orcid.org/0000-0001-5825-6859

Catalogue record

Date deposited: 03 Dec 2021 17:32
Last modified: 22 Jun 2022 02:06

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Contributors

Author: Paul Elliott
Author: David Haw
Author: Haowei Wang
Author: Oliver Eales
Author: Caroline E Walters
Author: Kylie E C Ainslie
Author: Christina Atchison
Author: Claudio Fronterre
Author: Peter J Diggle
Author: Andrew J Page
Author: Alexander J Trotter
Author: Sophie J Prosolek
Author: Deborah Ashby
Author: Christl A Donnelly
Author: Wendy Barclay
Author: Graham Taylor
Author: Graham Cooke
Author: Helen Ward
Author: Ara Darzi
Author: Steven Riley
Author: Samuel C Robson
Author: Nicholas J Loman
Author: Thomas R Connor
Author: Tanya Golubchik
Author: Rocio T Martinez Nunez
Author: Kordo Saeed ORCID iD
Author: Jacqui A Prieto ORCID iD
Author: James G Shepherd
Author: Matthew D Parker
Author: David A Simpson
Author: Christopher R Jones
Author: Christopher Holmes
Author: Thomas Williams
Author: Christopher Moore
Author: Hannah Paul
Author: Charlotte A Williams
Author: Sarah Taylor
Author: Sophie Jones
Author: Rachel Jones
Author: Jamie Young
Author: Minal Patel
Author: Louise Smith
Author: David G Partridge
Author: James W Harrison ORCID iD
Author: David Williams ORCID iD
Author: Clare Pearson
Author: Richard Gregory
Author: David J Baker
Author: Rachel M Tucker
Author: Rebecca Brown ORCID iD
Corporate Author: COVID-19 Genomics UK (COG-UK) Consortium11‡

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