Impact of vaccination on new SARS-CoV-2 infections in the United Kingdom

Emma Pritchard, Philippa C. Matthews, Nicole Stoesser, David W. Eyre, Owen Gethings, Karina Doris Vihta, Joel Jones, Thomas House, Harper VanSteenHouse, Iain Bell, John I. Bell, John N. Newton, Jeremy Farrar, Ian Diamond, Emma Rourke, Ruth Studley, Derrick Crook, Tim E.A. Peto, A. Sarah Walker, Koen B. Pouwels*

*Corresponding author for this work

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    The effectiveness of COVID-19 vaccination in preventing new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in the general community is still unclear. Here, we used the Office for National Statistics COVID-19 Infection Survey—a large community-based survey of individuals living in randomly selected private households across the United Kingdom—to assess the effectiveness of the BNT162b2 (Pfizer–BioNTech) and ChAdOx1 nCoV-19 (Oxford–AstraZeneca; ChAdOx1) vaccines against any new SARS-CoV-2 PCR-positive tests, split according to self-reported symptoms, cycle threshold value (<30 versus ≥30; as a surrogate for viral load) and gene positivity pattern (compatible with B.1.1.7 or not). Using 1,945,071 real-time PCR results from nose and throat swabs taken from 383,812 participants between 1 December 2020 and 8 May 2021, we found that vaccination with the ChAdOx1 or BNT162b2 vaccines already reduced SARS-CoV-2 infections ≥21 d after the first dose (61% (95% confidence interval (CI) = 54–68%) versus 66% (95% CI = 60–71%), respectively), with greater reductions observed after a second dose (79% (95% CI = 65–88%) versus 80% (95% CI = 73–85%), respectively). The largest reductions were observed for symptomatic infections and/or infections with a higher viral burden. Overall, COVID-19 vaccination reduced the number of new SARS-CoV-2 infections, with the largest benefit received after two vaccinations and against symptomatic and high viral burden infections, and with no evidence of a difference between the BNT162b2 and ChAdOx1 vaccines.

    Original languageEnglish
    Pages (from-to)1370-1378
    Number of pages9
    JournalNature Medicine
    Issue number8
    Early online date9 Jun 2021
    Publication statusPublished - Aug 2021

    Bibliographical note

    Funding Information: This study was funded by the Department of Health and Social Care, with in-kind support from the Welsh Government, Department of Health (on behalf of the Northern Ireland Government) and Scottish Government. E.P., K.B.P., A.S.W., T.E.A.P., N.S. and D.W.E. are supported by the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Healthcare Associated Infections and Antimicrobial Resistance at the University of Oxford in partnership with Public Health England (PHE) (NIHR200915). A.S.W. and T.E.A.P. are also supported by the NIHR Oxford Biomedical Research Centre. E.P. and K.B.P. are also supported by the Huo Family Foundation. A.S.W. is also supported by core support from the Medical Research Council UK to the MRC Clinical Trials Unit (MC_UU_12023/22) and is an NIHR Senior Investigator. P.C.M. is funded by the Wellcome Trust (intermediate fellowship; grant reference 110110/Z/15/Z) and holds an NIHR Oxford BRC Senior Fellowship award. D.W.E. is supported by a Robertson Fellowship and an NIHR Oxford BRC Senior Fellowship. The views expressed are those of the authors and not necessarily those of the National Health Service, NIHR, Department of Health or PHE. The funders/sponsors did not have any role in the design and conduct of the study; collection, management, analysis and interpretation of the data; preparation, review or approval of the manuscript; or decision to submit the manuscript for publication. All authors had full access to all data analysis outputs (reports and tables) and take responsibility for their integrity and accuracy. We are grateful for the support of all COVID-19 Infection Survey participants and the COVID-19 Infection Survey team.
    All authors have completed the International Committee of Medical Journal Editors uniform disclosure from at D.W.E. declares lecture fees from Gilead outside of the submitted work. E.P., P.C.M., N.S., D.W.E., J.I.B., D.C., T.E.A.P., A.S.W. and K.B.P. are employees of the University of Oxford but were not involved in the development or production of the ChAdOx1 vaccine. J.I.B. acts as an unpaid advisor to Her Majesty’s Government on COVID-19 but does not sit on the vaccine task force and is not involved in procurement decisions. J.I.B. also sits on the board of Oxford Sciences Innovation, which has an investment in Vaccitech, which will receive a royalty from the ChAdOx1 vaccine if/when it makes a profit. H.V. reports personal fees from BioSpyder Technologies outside of the submitted work. Besides the funding mentioned above, A.S.W. also received grants from the Medical Research Council UK during the conduct of the study. There are no other relationships or activities that could appear to have influenced the submitted work.

    Open Access: This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit

    Publisher Copyright: © 2021, The Author(s).

    Citation: Pritchard, E., Matthews, P.C., Stoesser, N. et al. Impact of vaccination on new SARS-CoV-2 infections in the United Kingdom. Nat Med 27, 1370–1378 (2021).



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