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Effect of Delta variant on viral burden and vaccine effectiveness against new SARS-CoV-2 infections in the UK.
Nat Med. 2021 12; 27(12):2127-2135.NMed

Abstract

The effectiveness of the BNT162b2 and ChAdOx1 vaccines against new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections requires continuous re-evaluation, given the increasingly dominant B.1.617.2 (Delta) variant. In this study, we investigated the effectiveness of these vaccines in a large, community-based survey of randomly selected households across the United Kingdom. We found that the effectiveness of BNT162b2 and ChAdOx1 against infections (new polymerase chain reaction (PCR)-positive cases) with symptoms or high viral burden is reduced with the B.1.617.2 variant (absolute difference of 10-13% for BNT162b2 and 16% for ChAdOx1) compared to the B.1.1.7 (Alpha) variant. The effectiveness of two doses remains at least as great as protection afforded by prior natural infection. The dynamics of immunity after second doses differed significantly between BNT162b2 and ChAdOx1, with greater initial effectiveness against new PCR-positive cases but faster declines in protection against high viral burden and symptomatic infection with BNT162b2. There was no evidence that effectiveness varied by dosing interval, but protection was higher in vaccinated individuals after a prior infection and in younger adults. With B.1.617.2, infections occurring after two vaccinations had similar peak viral burden as those in unvaccinated individuals. SARS-CoV-2 vaccination still reduces new infections, but effectiveness and attenuation of peak viral burden are reduced with B.1.617.2.

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Authors+Show Affiliations

Pouwels KB
National Institute for Health Research Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK. koen.pouwels@ndph.ox.ac.uk. Health Economics Research Centre, Nuffield Department of Population Health, University of Oxford, Oxford, UK. koen.pouwels@ndph.ox.ac.uk.
Pritchard E
National Institute for Health Research Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK. Nuffield Department of Medicine, University of Oxford, Oxford, UK.
Matthews PC
Nuffield Department of Medicine, University of Oxford, Oxford, UK. Department of Infectious Diseases and Microbiology, Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Oxford, UK. National Institute for Health Research Oxford Biomedical Research Centre, University of Oxford, Oxford, UK.
Stoesser N
National Institute for Health Research Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK. Nuffield Department of Medicine, University of Oxford, Oxford, UK. Department of Infectious Diseases and Microbiology, Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Oxford, UK. National Institute for Health Research Oxford Biomedical Research Centre, University of Oxford, Oxford, UK.
Eyre DW
National Institute for Health Research Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK. Nuffield Department of Medicine, University of Oxford, Oxford, UK. Department of Infectious Diseases and Microbiology, Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Oxford, UK. Big Data Institute, Nuffield Department of Population Health, University of Oxford, Oxford, UK.
Vihta KD
National Institute for Health Research Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK. Department of Engineering, University of Oxford, Oxford, UK.
House T
Department of Mathematics, University of Manchester, Manchester, UK. IBM Research, Hartree Centre, Sci-Tech Daresbury, UK.
Hay J
Glasgow Lighthouse Laboratory, Glasgow, UK. University of Glasgow, Glasgow, UK.
Bell JI
Office of the Regius Professor of Medicine, University of Oxford, Oxford, UK.
Newton JN
Health Improvement Directorate, Public Health England, London, UK.
Farrar J
Wellcome Trust, London, UK.
Crook D
National Institute for Health Research Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK. Nuffield Department of Medicine, University of Oxford, Oxford, UK. Department of Infectious Diseases and Microbiology, Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Oxford, UK. National Institute for Health Research Oxford Biomedical Research Centre, University of Oxford, Oxford, UK.
Cook D
Office for National Statistics, Newport, UK.
Rourke E
Office for National Statistics, Newport, UK.
Studley R
Office for National Statistics, Newport, UK.
Peto TEA
National Institute for Health Research Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK. Nuffield Department of Medicine, University of Oxford, Oxford, UK. Department of Infectious Diseases and Microbiology, Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Oxford, UK. National Institute for Health Research Oxford Biomedical Research Centre, University of Oxford, Oxford, UK.
Diamond I
Office for National Statistics, Newport, UK.
Walker AS
National Institute for Health Research Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK. Nuffield Department of Medicine, University of Oxford, Oxford, UK. Department of Infectious Diseases and Microbiology, Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Oxford, UK. MRC Clinical Trials Unit at UCL, University College London, London, UK.

MeSH

AdolescentAdultAntibodies, NeutralizingAntibodies, ViralBNT162 VaccineCOVID-19ChAdOx1 nCoV-19HumansMiddle AgedPolymerase Chain ReactionSARS-CoV-2United KingdomVaccinationVaccine EfficacyViral LoadYoung Adult

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

34650248

Citation

Pouwels, Koen B., et al. "Effect of Delta Variant On Viral Burden and Vaccine Effectiveness Against New SARS-CoV-2 Infections in the UK." Nature Medicine, vol. 27, no. 12, 2021, pp. 2127-2135.
Pouwels KB, Pritchard E, Matthews PC, et al. Effect of Delta variant on viral burden and vaccine effectiveness against new SARS-CoV-2 infections in the UK. Nat Med. 2021;27(12):2127-2135.
Pouwels, K. B., Pritchard, E., Matthews, P. C., Stoesser, N., Eyre, D. W., Vihta, K. D., House, T., Hay, J., Bell, J. I., Newton, J. N., Farrar, J., Crook, D., Cook, D., Rourke, E., Studley, R., Peto, T. E. A., Diamond, I., & Walker, A. S. (2021). Effect of Delta variant on viral burden and vaccine effectiveness against new SARS-CoV-2 infections in the UK. Nature Medicine, 27(12), 2127-2135. https://doi.org/10.1038/s41591-021-01548-7
Pouwels KB, et al. Effect of Delta Variant On Viral Burden and Vaccine Effectiveness Against New SARS-CoV-2 Infections in the UK. Nat Med. 2021;27(12):2127-2135. PubMed PMID: 34650248.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of Delta variant on viral burden and vaccine effectiveness against new SARS-CoV-2 infections in the UK. AU - Pouwels,Koen B, AU - Pritchard,Emma, AU - Matthews,Philippa C, AU - Stoesser,Nicole, AU - Eyre,David W, AU - Vihta,Karina-Doris, AU - House,Thomas, AU - Hay,Jodie, AU - Bell,John I, AU - Newton,John N, AU - Farrar,Jeremy, AU - Crook,Derrick, AU - Cook,Duncan, AU - Rourke,Emma, AU - Studley,Ruth, AU - Peto,Tim E A, AU - Diamond,Ian, AU - Walker,A Sarah, Y1 - 2021/10/14/ PY - 2021/08/18/received PY - 2021/09/21/accepted PY - 2021/10/16/pubmed PY - 2022/1/6/medline PY - 2021/10/15/entrez SP - 2127 EP - 2135 JF - Nature medicine JO - Nat Med VL - 27 IS - 12 N2 - The effectiveness of the BNT162b2 and ChAdOx1 vaccines against new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections requires continuous re-evaluation, given the increasingly dominant B.1.617.2 (Delta) variant. In this study, we investigated the effectiveness of these vaccines in a large, community-based survey of randomly selected households across the United Kingdom. We found that the effectiveness of BNT162b2 and ChAdOx1 against infections (new polymerase chain reaction (PCR)-positive cases) with symptoms or high viral burden is reduced with the B.1.617.2 variant (absolute difference of 10-13% for BNT162b2 and 16% for ChAdOx1) compared to the B.1.1.7 (Alpha) variant. The effectiveness of two doses remains at least as great as protection afforded by prior natural infection. The dynamics of immunity after second doses differed significantly between BNT162b2 and ChAdOx1, with greater initial effectiveness against new PCR-positive cases but faster declines in protection against high viral burden and symptomatic infection with BNT162b2. There was no evidence that effectiveness varied by dosing interval, but protection was higher in vaccinated individuals after a prior infection and in younger adults. With B.1.617.2, infections occurring after two vaccinations had similar peak viral burden as those in unvaccinated individuals. SARS-CoV-2 vaccination still reduces new infections, but effectiveness and attenuation of peak viral burden are reduced with B.1.617.2. SN - 1546-170X UR - https://www.unboundmedicine.com/medline/citation/34650248/Effect_of_Delta_variant_on_viral_burden_and_vaccine_effectiveness_against_new_SARS_CoV_2_infections_in_the_UK_ DB - PRIME DP - Unbound Medicine ER -