Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Clinical Trial
. 2021 Apr 10;397(10282):1351-1362.
doi: 10.1016/S0140-6736(21)00628-0. Epub 2021 Mar 30.

Efficacy of ChAdOx1 nCoV-19 (AZD1222) vaccine against SARS-CoV-2 variant of concern 202012/01 (B.1.1.7): an exploratory analysis of a randomised controlled trial

Katherine R W Emary  1 Tanya Golubchik  2 Parvinder K Aley  1 Cristina V Ariani  3 Brian Angus  4 Sagida Bibi  1 Beth Blane  5 David Bonsall  6 Paola Cicconi  4 Sue Charlton  7 Elizabeth A Clutterbuck  1 Andrea M Collins  8 Tony Cox  9 Thomas C Darton  10 Christina Dold  1 Alexander D Douglas  4 Christopher J A Duncan  11 Katie J Ewer  4 Amy L Flaxman  4 Saul N Faust  12 Daniela M Ferreira  8 Shuo Feng  1 Adam Finn  13 Pedro M Folegatti  4 Michelle Fuskova  4 Eva Galiza  14 Anna L Goodman  15 Catherine M Green  16 Christopher A Green  17 Melanie Greenland  1 Bassam Hallis  7 Paul T Heath  14 Jodie Hay  18 Helen C Hill  8 Daniel Jenkin  4 Simon Kerridge  1 Rajeka Lazarus  19 Vincenzo Libri  20 Patrick J Lillie  21 Catherine Ludden  5 Natalie G Marchevsky  1 Angela M Minassian  4 Alastair C McGregor  22 Yama F Mujadidi  1 Daniel J Phillips  1 Emma Plested  1 Katrina M Pollock  23 Hannah Robinson  1 Andrew Smith  24 Rinn Song  1 Matthew D Snape  1 Rebecca K Sutherland  25 Emma C Thomson  26 Mark Toshner  27 David P J Turner  28 Johan Vekemans  29 Tonya L Villafana  29 Christopher J Williams  30 Adrian V S Hill  4 Teresa Lambe  1 Sarah C Gilbert  4 Merryn Voysey  1 Maheshi N Ramasamy  31 Andrew J Pollard  1 COVID-19 Genomics UK consortiumAMPHEUS ProjectOxford COVID-19 Vaccine Trial Group
Affiliations
Clinical Trial

Efficacy of ChAdOx1 nCoV-19 (AZD1222) vaccine against SARS-CoV-2 variant of concern 202012/01 (B.1.1.7): an exploratory analysis of a randomised controlled trial

Katherine R W Emary et al. Lancet. .

Abstract

Background: A new variant of SARS-CoV-2, B.1.1.7, emerged as the dominant cause of COVID-19 disease in the UK from November, 2020. We report a post-hoc analysis of the efficacy of the adenoviral vector vaccine, ChAdOx1 nCoV-19 (AZD1222), against this variant.

Methods: Volunteers (aged ≥18 years) who were enrolled in phase 2/3 vaccine efficacy studies in the UK, and who were randomly assigned (1:1) to receive ChAdOx1 nCoV-19 or a meningococcal conjugate control (MenACWY) vaccine, provided upper airway swabs on a weekly basis and also if they developed symptoms of COVID-19 disease (a cough, a fever of 37·8°C or higher, shortness of breath, anosmia, or ageusia). Swabs were tested by nucleic acid amplification test (NAAT) for SARS-CoV-2 and positive samples were sequenced through the COVID-19 Genomics UK consortium. Neutralising antibody responses were measured using a live-virus microneutralisation assay against the B.1.1.7 lineage and a canonical non-B.1.1.7 lineage (Victoria). The efficacy analysis included symptomatic COVID-19 in seronegative participants with a NAAT positive swab more than 14 days after a second dose of vaccine. Participants were analysed according to vaccine received. Vaccine efficacy was calculated as 1 - relative risk (ChAdOx1 nCoV-19 vs MenACWY groups) derived from a robust Poisson regression model. This study is continuing and is registered with ClinicalTrials.gov, NCT04400838, and ISRCTN, 15281137.

Findings: Participants in efficacy cohorts were recruited between May 31 and Nov 13, 2020, and received booster doses between Aug 3 and Dec 30, 2020. Of 8534 participants in the primary efficacy cohort, 6636 (78%) were aged 18-55 years and 5065 (59%) were female. Between Oct 1, 2020, and Jan 14, 2021, 520 participants developed SARS-CoV-2 infection. 1466 NAAT positive nose and throat swabs were collected from these participants during the trial. Of these, 401 swabs from 311 participants were successfully sequenced. Laboratory virus neutralisation activity by vaccine-induced antibodies was lower against the B.1.1.7 variant than against the Victoria lineage (geometric mean ratio 8·9, 95% CI 7·2-11·0). Clinical vaccine efficacy against symptomatic NAAT positive infection was 70·4% (95% CI 43·6-84·5) for B.1.1.7 and 81·5% (67·9-89·4) for non-B.1.1.7 lineages.

Interpretation: ChAdOx1 nCoV-19 showed reduced neutralisation activity against the B.1.1.7 variant compared with a non-B.1.1.7 variant in vitro, but the vaccine showed efficacy against the B.1.1.7 variant of SARS-CoV-2.

Funding: UK Research and Innovation, National Institute for Health Research (NIHR), Coalition for Epidemic Preparedness Innovations, NIHR Oxford Biomedical Research Centre, Thames Valley and South Midlands NIHR Clinical Research Network, and AstraZeneca.

PubMed Disclaimer

Conflict of interest statement

Declaration of interests Oxford University has entered into a partnership with AstraZeneca for further development of ChAdOx1 nCoV-19. AstraZeneca reviewed the data from the study and the final manuscript before submission but the authors retained editorial control. SCG is cofounder of Vaccitech (collaborators in the early development of this vaccine candidate) and is named as an inventor on a patent covering use of ChAdOx1-vectored vaccines (PCT/GB2012/000467) and a patent application covering this SARS-CoV-2 vaccine. TL is named as an inventor on a patent application covering this SARS-CoV-2 vaccine and was a consultant to Vaccitech. PMF is a consultant to Vaccitech. AJP is chair of the UK Department of Health and Social Care Joint Committee on Vaccination and Immunisation but does not participate in policy advice on coronavirus vaccines, and is a member of the WHO Strategic Advisory Group of Experts. AJP and SNF are NIHR senior investigators. AVSH is a cofounder of and consultant to Vaccitech and is named as an inventor on a patent covering design and use of ChAdOx1-vectored vaccines (PCT/GB2012/000467). MDS reports grants from Janssen, GlaxoSmithKline, Medimmune, Novavax, and MCM Vaccine, and grants and non-financial support from Pfizer outside of the submitted work. CMG reports personal fees from the Duke Human Vaccine Institute outside of the submitted work. ADD reports grants and personal fees from AstraZeneca outside of the submitted work. SNF reports grants from Janssen and Valneva outside of the submitted work. TLV and JV are employees of AstraZeneca. All other authors declare no competing interests.

Figures

Figure 1
Figure 1
Flow diagram of swabs included in the analysis
Figure 2
Figure 2
Consensus phylogeny of SARS-CoV-2 genomes identified in this study Clades are coloured by variant lineage and tips are coloured by vaccine allocation. Only genomes with at least 40% coverage are included (n=247). Lineages were assigned by Pangolin version 2.1.7 (lineages version 2021–02–12).
Figure 3
Figure 3
Weekly and cumulative number of B.1.1.7 and non-B.1.1.7 isolates identified in the UK trial between Oct 1, 2020, and Jan 14, 2021 Bars show overall weekly case counts (left axis) and lines show cumulative case counts (right axis).
Figure 4
Figure 4
Minimum Ct values across all NAAT positive swabs Ct values from positive NAATs performed at Lighthouse Laboratories using a ThermoFisher TaqPath three-gene assay. Each datapoint represents one participant. For each participant, the minimum of the Ct value for the N gene and ORF1ab gene was taken for each NAAT positive swab, and the minimum across all swabs for the same participant was calculated as a proxy for maximum viral load. Low Ct values are associated with a higher viral load. The midlines of the boxes show medians and the outer bounds of the boxes show IQRs. Error bars show the most extreme point within 1.5 × IQR above or below the 75th or 25th percentile. Ct=cycle threshold. NAAT=nucleic acid amplification test.
Figure 5
Figure 5
Length of the NAAT-positive period per participant Three primary symptomatic participants who received ChAdOx1 nCoV-19 remained NAAT positive for 8, 9, and 11 weeks, respectively, and one primary symptomatic participant who received the control vaccine remained NAAT positive for 11 weeks; these cases are not shown in the figure. NAAT=nucleic acid amplification test.
Figure 6
Figure 6
Live-virus microneutralisation antibody titres of sera against B.1.1.7 and a canonical non-B.1.1.7 strain (Victoria) The geometric mean titre is 58 (95% CI 44–77) for B.1.1.7 and 517 (424–631) for Victoria. The geometric mean ratio (Victoria vs B.1.1.7) is 8·9 (95% CI 7·2–11·0). The midlines of the boxes show medians and the outer bounds of the boxes show IQRs. Error bars show the most extreme point within 1·5 × IQR above or below the 75th or 25th percentile. Lines connect samples from the same participant collected at the same trial timepoint (n=49). ND50=titre at which 50% virus neutralisation is achieved.

Comment in

Similar articles

  • Review of Covid-19 vaccine clinical trials - A puzzle with missing pieces.
    Kwok HF. Kwok HF. Int J Biol Sci. 2021 Apr 10;17(6):1461-1468. doi: 10.7150/ijbs.59170. eCollection 2021. Int J Biol Sci. 2021. PMID: 33907509 Free PMC article. Review.
  • Single-dose administration and the influence of the timing of the booster dose on immunogenicity and efficacy of ChAdOx1 nCoV-19 (AZD1222) vaccine: a pooled analysis of four randomised trials.
    Voysey M, Costa Clemens SA, Madhi SA, Weckx LY, Folegatti PM, Aley PK, Angus B, Baillie VL, Barnabas SL, Bhorat QE, Bibi S, Briner C, Cicconi P, Clutterbuck EA, Collins AM, Cutland CL, Darton TC, Dheda K, Dold C, Duncan CJA, Emary KRW, Ewer KJ, Flaxman A, Fairlie L, Faust SN, Feng S, Ferreira DM, Finn A, Galiza E, Goodman AL, Green CM, Green CA, Greenland M, Hill C, Hill HC, Hirsch I, Izu A, Jenkin D, Joe CCD, Kerridge S, Koen A, Kwatra G, Lazarus R, Libri V, Lillie PJ, Marchevsky NG, Marshall RP, Mendes AVA, Milan EP, Minassian AM, McGregor A, Mujadidi YF, Nana A, Padayachee SD, Phillips DJ, Pittella A, Plested E, Pollock KM, Ramasamy MN, Ritchie AJ, Robinson H, Schwarzbold AV, Smith A, Song R, Snape MD, Sprinz E, Sutherland RK, Thomson EC, Török ME, Toshner M, Turner DPJ, Vekemans J, Villafana TL, White T, Williams CJ, Douglas AD, Hill AVS, Lambe T, Gilbert SC, Pollard AJ; Oxford COVID Vaccine Trial Group. Voysey M, et al. Lancet. 2021 Mar 6;397(10277):881-891. doi: 10.1016/S0140-6736(21)00432-3. Epub 2021 Feb 19. Lancet. 2021. PMID: 33617777 Free PMC article.
  • Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) against SARS-CoV-2: an interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK.
    Voysey M, Clemens SAC, Madhi SA, Weckx LY, Folegatti PM, Aley PK, Angus B, Baillie VL, Barnabas SL, Bhorat QE, Bibi S, Briner C, Cicconi P, Collins AM, Colin-Jones R, Cutland CL, Darton TC, Dheda K, Duncan CJA, Emary KRW, Ewer KJ, Fairlie L, Faust SN, Feng S, Ferreira DM, Finn A, Goodman AL, Green CM, Green CA, Heath PT, Hill C, Hill H, Hirsch I, Hodgson SHC, Izu A, Jackson S, Jenkin D, Joe CCD, Kerridge S, Koen A, Kwatra G, Lazarus R, Lawrie AM, Lelliott A, Libri V, Lillie PJ, Mallory R, Mendes AVA, Milan EP, Minassian AM, McGregor A, Morrison H, Mujadidi YF, Nana A, O'Reilly PJ, Padayachee SD, Pittella A, Plested E, Pollock KM, Ramasamy MN, Rhead S, Schwarzbold AV, Singh N, Smith A, Song R, Snape MD, Sprinz E, Sutherland RK, Tarrant R, Thomson EC, Török ME, Toshner M, Turner DPJ, Vekemans J, Villafana TL, Watson MEE, Williams CJ, Douglas AD, Hill AVS, Lambe T, Gilbert SC, Pollard AJ; Oxford COVID Vaccine Trial Group. Voysey M, et al. Lancet. 2021 Jan 9;397(10269):99-111. doi: 10.1016/S0140-6736(20)32661-1. Epub 2020 Dec 8. Lancet. 2021. PMID: 33306989 Free PMC article. Clinical Trial.
  • Safety and immunogenicity of ChAdOx1 nCoV-19 vaccine administered in a prime-boost regimen in young and old adults (COV002): a single-blind, randomised, controlled, phase 2/3 trial.
    Ramasamy MN, Minassian AM, Ewer KJ, Flaxman AL, Folegatti PM, Owens DR, Voysey M, Aley PK, Angus B, Babbage G, Belij-Rammerstorfer S, Berry L, Bibi S, Bittaye M, Cathie K, Chappell H, Charlton S, Cicconi P, Clutterbuck EA, Colin-Jones R, Dold C, Emary KRW, Fedosyuk S, Fuskova M, Gbesemete D, Green C, Hallis B, Hou MM, Jenkin D, Joe CCD, Kelly EJ, Kerridge S, Lawrie AM, Lelliott A, Lwin MN, Makinson R, Marchevsky NG, Mujadidi Y, Munro APS, Pacurar M, Plested E, Rand J, Rawlinson T, Rhead S, Robinson H, Ritchie AJ, Ross-Russell AL, Saich S, Singh N, Smith CC, Snape MD, Song R, Tarrant R, Themistocleous Y, Thomas KM, Villafana TL, Warren SC, Watson MEE, Douglas AD, Hill AVS, Lambe T, Gilbert SC, Faust SN, Pollard AJ; Oxford COVID Vaccine Trial Group. Ramasamy MN, et al. Lancet. 2021 Dec 19;396(10267):1979-1993. doi: 10.1016/S0140-6736(20)32466-1. Epub 2020 Nov 19. Lancet. 2021. PMID: 33220855 Free PMC article. Clinical Trial.
  • Safety and immunogenicity of the ChAdOx1 nCoV-19 vaccine against SARS-CoV-2: a preliminary report of a phase 1/2, single-blind, randomised controlled trial.
    Folegatti PM, Ewer KJ, Aley PK, Angus B, Becker S, Belij-Rammerstorfer S, Bellamy D, Bibi S, Bittaye M, Clutterbuck EA, Dold C, Faust SN, Finn A, Flaxman AL, Hallis B, Heath P, Jenkin D, Lazarus R, Makinson R, Minassian AM, Pollock KM, Ramasamy M, Robinson H, Snape M, Tarrant R, Voysey M, Green C, Douglas AD, Hill AVS, Lambe T, Gilbert SC, Pollard AJ; Oxford COVID Vaccine Trial Group. Folegatti PM, et al. Lancet. 2020 Aug 15;396(10249):467-478. doi: 10.1016/S0140-6736(20)31604-4. Epub 2020 Jul 20. Lancet. 2020. PMID: 32702298 Free PMC article. Clinical Trial.

Cited by

References

    1. Polack FP, Thomas SJ, Kitchin N. Safety and efficacy of the BNT162b2 mRNA Covid-19 vaccine. N Engl J Med. 2020;383:2603–2615. - PMC - PubMed
    1. Baden LR, El Sahly HM, Essink B. Efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine. N Engl J Med. 2021;384:403–416. - PMC - PubMed
    1. Voysey M, Clemens SAC, Madhi SA. Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) against SARS-CoV-2: an interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK. Lancet. 2021;397:99–111. - PMC - PubMed
    1. Novavax Novavax COVID-19 vaccine demonstrates 89.3% efficacy in UK phase 3 trial. Jan 28, 2021. https://ir.novavax.com/news-releases/news-release-details/novavax-covid-...
    1. Janssen Johnson & Johnson announces single-shot Janssen COVID-19 vaccine candidate met primary endpoints in interim analysis of its phase 3 ENSEMBLE trial. Jan 29, 2021. https://www.janssen.com/johnson-johnson-announces-single-shot-janssen-co...

Publication types

MeSH terms

Associated data

-