Trial reportLancet (London, England)2021
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.
Erratum issued 12 registry-linked trialsOpen access · hybridAbstract readRandomized Controlled Trial
In one paragraph
Trial report in Lancet (London, England), 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. An erratum has been issued. It is linked to 12 registered trials, which are not on this map. Cited by 2,920 papers, 7 of them syntheses that pooled it.
0numbers the graph read from it
0cells of the map it votes in
2,920citing papers in PubMed, 7 pooled it
111.8field-weighted citation impact, top 1% of its field
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Pharmaco-epidemiological Study of COVID 19 Vaccines in Patients Undergoing Immunotherapy for Cancer. A Retrospective Open Cohort Study.
A Multicenter, Randomized, Double Blind, Controlled, Phase III Clinical Trial (Immunobridging Study) of Vaksin Merah Putih - UA SARS-CoV-2 (Vero Cell Inactivated) in Healthy Population Aged 18 Years and Above
NCT05918939 early_phase1unknown statusnot on this mapstarted 2022, after this paper: background citation
Immunobridging Study: Immunogenicity and Safety of Vaksin Merah Putih - UA SARS-CoV-2 (Vero Cell Inactivated) Vaccine as Heterologue Booster in Adult Subjects in Indonesia
NCT06259578 early_phase1unknown statusnot on this mapstarted 2024, after this paper: background citation
Immunobridging Study: Immunogenicity and Safety of INAVAC (Vaksin Merah Putih - UNAIR SARS-CoV-2 (Vero Cell Inactivated)) Vaccine as Homologue Booster in Adult Subjects in Indonesia
NCT06272253 early_phase1unknown statusnot on this mapstarted 2023, after this paper: background citation
Immunobridging Study: Immunogenicity and Safety of INAVAC (Vaksin Merah Putih - UNAIR SARS-CoV-2 (Vero Cell Inactivated)) as Heterologue Booster in Adolescent Subjects in Indonesia
An Open Label, Phase III Clinical Trial (Immunobridging Study) of INAVAC (Vaksin Merah Putih - UA-SARS CoV-2 (Vero Cell Inactivated)) in Healthy Population Aged 12 to 17 Years Old
Who cites it
2,920 citing papers in PubMed, 7 syntheses or guidelines pooled it, 4,980 citations in OpenAlex.
- The efficacy and effectiveness of COVID-19 vaccines in Iran: a systematic review and meta-analysis.BMC infectious diseases · 2025Pooled it
- A meta-analysis of vaccine efficacy from phase III clinical trials of approved vaccines against SARS-CoV-2 and variants.BMC infectious diseases · 2025Pooled it
- Effectiveness of interventions to improve vaccine efficacy: a systematic review and meta-analysis.Systematic reviews · 2025Pooled it
- Globally approved vaccines for COVID-19: a systematic review.Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology] · 2025Pooled it
- CT scan-derived pectoralis muscle parameters are closely associated with COVID-19 outcomes: A systematic review and meta-analysis.PloS one · 2025Pooled it
- Immunogenicity of COVID-19 vaccines in patients with cirrhosis: A meta-analysis.Human vaccines & immunotherapeutics · 2024Pooled it
- Immune response of COVID-19 vaccines in solid cancer patients: A meta-analysis.Human vaccines & immunotherapeutics · 2024Pooled it
- Could β-glucans enhance the immune response to SARS-CoV-2 vaccine by inducing trained immunity and boosting neutralizing antibody production?Frontiers in immunology · 2026Trial
- Phase 2/3 study evaluating safety, immunogenicity, and noninferiority of single booster dose of AVX/COVID-12 vaccine.Science advances · 2025Trial
- SARS-Cov-2 vaccination strategies in hospitalized recovered COVID-19 patients: a randomized clinical trial (VATICO Trial).Scientific reports · 2025Trial
- Trial
- Predictors of COVID-19 vaccination status among youth in eThekwini, South Africa: results from the AYAZAZI RIGHTS study.Global health action · 2026Article
- Respiratory mucosal immunity: Biological functions, diseases, prevention and therapy.Genes & diseases · 2026Review
- Two Versus One COVID-19 Vaccine Dose After Prior SARS-CoV-2 Infection: A Nationwide Retrospective Cohort Study.Open forum infectious diseases · 2026Article
- A predictive model for rapid assessment of protective efficacy against emerging SARS-CoV-2 variants.Infectious Disease Modelling · 2026Article
- Bovine Adenovirus 3-Based Viral Vectors for Veterinary Vaccine Development: Progress, Limitations, and Future Directions.Veterinary sciences · 2026Review
- Synthesis of 1,3,5-Triazine-Indole Conjugates as Broad-Spectrum Coronavirus Entry Inhibitors.ChemMedChem · 2026Article
- Vaccination-first immune priming shapes a sustained mRNA vaccine-induced IgG4 class switch that associates with SARS-CoV-2 breakthrough infection risk.Scientific reports · 2026Article
- The immunogenicity and safety of adenoviral-based vaccines.Current opinion in allergy and clinical immunology · 2026Review
- Six Years of COVID-19: Lessons from Epidemiology, Vaccination Campaigns, Clinical Risk Stratification, and Thromboembolic Surveillance.Vaccines · 2026Review
2,860 more citing papers are in PubMed but not listed here.
Corrections and comments
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- Erratum issued
Authors and funding
83 authors at 20 institutions in 6 countries.
Merryn VoyseyOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.
Sue Ann Costa ClemensInstitute of Global Health, University of Siena, Siena, Brazil; Department of Paediatrics, University of Oxford, Oxford, UK.
Shabir A MadhiMRC Vaccines and Infectious Diseases Analytics Research Unit, Johannesburg, South Africa.
Lily Y WeckxDepartment of Pediatrics, Universidade Federal de São Paulo, São Paulo, Brazil.
Pedro M FolegattiJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Parvinder K AleyOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.
Brian AngusJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Vicky L BaillieRespiratory and Meningeal Pathogens Research Unit, University of the Witwatersrand, Johannesburg, South Africa.
Shaun L BarnabasFamily Centre for Research with Ubuntu, Department of Paediatrics, University of Stellenbosch, Cape Town, South Africa.
Qasim E BhoratSoweto Clinical Trials Centre, Soweto, South Africa.
Sagida BibiOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.
Carmen BrinerPerinatal HIV Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
Paola CicconiJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Andrea M CollinsDepartment of Clinical Sciences, Liverpool School of Tropical Medicine and Liverpool University Hospitals NHS Foundation Trust, Liverpool, UK.
Rachel Colin-JonesOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.
Clare L CutlandRespiratory and Meningeal Pathogens Research Unit, University of the Witwatersrand, Johannesburg, South Africa.
Thomas C DartonDepartment of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, UK; Department of Infection and Tropical Medicine, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK.
Keertan DhedaDivision of Pulmonology, Groote Schuur Hospital and the University of Cape Town, South Africa; Faculty of Infectious and Tropical Diseases, Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK.
Christopher J A DuncanDepartment of Infection and Tropical Medicine, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK; Translational and Clinical Research Institute, Immunity and Inflammation Theme, Newcastle University, Newcastle upon Tyne, UK.
Katherine R W EmaryOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.
Katie J EwerJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Lee FairlieWits Reproductive Health and HIV Institute, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
Saul N FaustNIHR Southampton Clinical Research Facility and Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust, Southampton, UK; Faculty of Medicine and Institute for Life Sciences, University of Southampton, Southampton, UK.
Shuo FengOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.
Daniela M FerreiraDepartment of Clinical Sciences, Liverpool School of Tropical Medicine and Liverpool University Hospitals NHS Foundation Trust, Liverpool, UK.
Adam FinnSchool of Population Health Sciences, University of Bristol and University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, UK.
Anna L GoodmanDepartment of Infection, Guy's and St Thomas' NHS Foundation Trust, St Thomas' Hospital, London, UK; MRC Clinical Trials Unit, University College London, London, UK.
Catherine M GreenClinical BioManufacturing Facility, University of Oxford, Oxford, UK.
Christopher A GreenNIHR/Wellcome Trust Clinical Research Facility, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK.
Paul T HeathSt George's Vaccine Institute, St George's, University of London, London, UK.
Catherine HillWits Reproductive Health and HIV Institute, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
Helen HillDepartment of Clinical Sciences, Liverpool School of Tropical Medicine and Liverpool University Hospitals NHS Foundation Trust, Liverpool, UK.
Ian HirschAstraZeneca BioPharmaceuticals, Cambridge, UK.
Susanne H C HodgsonJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Alane IzuVIDA-Vaccines and Infectious Diseases Analytical Research Unit, Johannesburg, South Africa.
Susan JacksonJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Daniel JenkinJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Carina C D JoeJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Simon KerridgeOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.
Anthonet KoenVIDA-Vaccines and Infectious Diseases Analytical Research Unit, Johannesburg, South Africa.
Gaurav KwatraWits Reproductive Health and HIV Institute, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
Rajeka LazarusSevern Pathology, North Bristol NHS Trust, Bristol, UK.
Alison M LawrieJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Alice LelliottOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.
Vincenzo LibriNIHR UCLH Clinical Research Facility and NIHR UCLH Biomedical Research Centre, London, UK.
Patrick J LillieDepartment of Infection, Hull University Teaching Hospitals NHS Trust, UK.
Raburn MalloryAstraZeneca BioPharmaceuticals, Cambridge, UK.
Ana V A MendesEscola Bahiana de Medicina e Saúde Pública, Salvador, Braziland Hospital São Rafael, Salvador, Brazil; Instituto D'Or, Salvador, Brazil.
Eveline P MilanDepartment of Infectious Diseases, Universidade Federal do Rio Grande do Norte, Natal, Brazil.
Angela M MinassianJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Alastair McGregorLondon Northwest University Healthcare, Harrow, UK.
Hazel MorrisonJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Yama F MujadidiOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.
Anusha NanaPerinatal HIV Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
Peter J O'ReillyOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.
Sherman D PadayacheeSetshaba Research Centre, Pretoria, South Africa.
Ana PittellaDepartment of Internal Medicine, Hospital Quinta D'Or, Rio de Janeiro, Brazil; Instituto D'Or de Pesquisa e Ensino (IDOR), Rio de Janeiro, Brazil; Department of Internal Medicine, Universidade UNIGRANRIO, Rio de Janeiro, Brazil.
Emma PlestedOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.
Katrina M PollockNIHR Imperial Clinical Research Facility and NIHR Imperial Biomedical Research Centre, London, UK.
Maheshi N RamasamyOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.
Sarah RheadOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.
Alexandre V SchwarzboldClinical Research Unit, Department of Clinical Medicine, Universidade Federal de Santa Maria, Santa Maria, Brazil.
Nisha SinghOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.
Andrew SmithCollege of Medical, Veterinary & Life Sciences, Glasgow Dental Hospital & School, University of Glasgow, Glasgow, UK.
Rinn SongOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK; Division of Infectious Diseases, Boston Children's Hospital, Boston, MA, USA.
Matthew D SnapeOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.
Eduardo SprinzInfectious Diseases Service, Hospital de Clinicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
Rebecca K SutherlandClinical Infection Research Group, Regional Infectious Diseases Unit, Western General Hospital, Edinburgh, UK.
Richard TarrantClinical BioManufacturing Facility, University of Oxford, Oxford, UK.
Emma C ThomsonMRC-University of Glasgow Centre for Virus Research & Department of Infectious Diseases, Queen Elizabeth University Hospital, Glasgow, UK.
M Estée TörökDepartment of Medicine, University of Cambridge, UK; Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
Mark ToshnerHeart Lung Research Institute, Department of Medicine, University of Cambridge and Royal Papworth Hospital NHS Foundation Trust, Cambridge, UK.
David P J TurnerUniversity of Nottingham and Nottingham University Hospitals NHS Trust, UK.
Johan VekemansAstraZeneca BioPharmaceuticals, Cambridge, UK.
Tonya L VillafanaAstraZeneca BioPharmaceuticals, Cambridge, UK.
Marion E E WatsonJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Christopher J WilliamsPublic Health Wales, Cardiff, Wales; Aneurin Bevan University Health Board, Newport, UK.
Alexander D DouglasJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Adrian V S HillJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Teresa LambeJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Sarah C GilbertJenner Institute, Nuffield Department of Medicine, University of Oxford, UK.
Andrew J PollardOxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK. Electronic address: andrew.pollard@paediatrics.ox.ac.uk.
Oxford COVID Vaccine Trial Group
University of Oxford · GBUniversity of London · GBUniversity of the Witwatersrand · ZAUCL Biomedical Research Centre · GBAstraZeneca (United Kingdom) · GBLiverpool School of Tropical Medicine · GBRight to Care · ZAUniversity Hospitals Birmingham NHS Foundation Trust · GBAneurin Bevan University Health Board · GBBoston Children's Hospital · USEscola Bahiana de Medicina e Saúde Pública · BRLondon North West Healthcare NHS Trust · GBMRC University of Glasgow Centre for Virus Research · GBNewcastle upon Tyne Hospitals NHS Foundation Trust · GBNIHR Imperial Biomedical Research Centre · GBNorth Bristol NHS Trust · GBNottingham University Hospitals NHS Trust · GBPapworth Hospital NHS Foundation Trust · GBSetshaba Research Centre · ZASheffield Teaching Hospitals NHS Foundation Trust · GB
Funding
Medical Research Council MC_PC_18058Medical Research Council MC_PC_19055Medical Research Council MC_UU_00004/04Medical Research Council MC_UU_12014/8Medical Research Council MC_UU_12023/22Medical Research Council MR/L006588/1Medical Research Council MR/N008219/1Medical Research Council MR/T001151/1Medical Research Council MR/T031891/1Wellcome Trust 109965/Z/15/ZWellcome Trust 211153/Z/18/Z
Abstract
backgroundA safe and efficacious vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), if deployed with high coverage, could contribute to the control of the COVID-19 pandemic. We evaluated the safety and efficacy of the ChAdOx1 nCoV-19 vaccine in a pooled interim analysis of four trials.
methodsThis analysis includes data from four ongoing blinded, randomised, controlled trials done across the UK, Brazil, and South Africa. Participants aged 18 years and older were randomly assigned (1:1) to ChAdOx1 nCoV-19 vaccine or control (meningococcal group A, C, W, and Y conjugate vaccine or saline). Participants in the ChAdOx1 nCoV-19 group received two doses containing 5 × 10
findingsBetween April 23 and Nov 4, 2020, 23 848 participants were enrolled and 11 636 participants (7548 in the UK, 4088 in Brazil) were included in the interim primary efficacy analysis. In participants who received two standard doses, vaccine efficacy was 62·1% (95% CI 41·0-75·7; 27 [0·6%] of 4440 in the ChAdOx1 nCoV-19 group vs71 [1·6%] of 4455 in the control group) and in participants who received a low dose followed by a standard dose, efficacy was 90·0% (67·4-97·0; three [0·2%] of 1367 vs 30 [2·2%] of 1374; p
interpretationChAdOx1 nCoV-19 has an acceptable safety profile and has been found to be efficacious against symptomatic COVID-19 in this interim analysis of ongoing clinical trials.
fundingUK Research and Innovation, National Institutes for Health Research (NIHR), Coalition for Epidemic Preparedness Innovations, Bill & Melinda Gates Foundation, Lemann Foundation, Rede D'Or, Brava and Telles Foundation, NIHR Oxford Biomedical Research Centre, Thames Valley and South Midland's NIHR Clinical Research Network, and AstraZeneca.
Indexed as
COVID-19 VaccinesAdolescentAdultAgedBrazilChAdOx1 nCoV-19COVID-19Double-Blind MethodFemaleHumansMaleMiddle AgedSingle-Blind MethodSouth AfricaTreatment OutcomeUnited KingdomChAdOx1 nCoV-19COVID-19 Vaccines
Identifiers
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Registered trials
NCT04738435ClinicalTrials.gov
NCT04843917ClinicalTrials.gov
NCT04878822ClinicalTrials.gov
NCT04914832ClinicalTrials.gov
NCT04944433ClinicalTrials.gov
NCT04961385ClinicalTrials.gov
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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.