Trial reportNature communications2021
Efficacy of ChAdOx1 nCoV-19 (AZD1222) vaccine against SARS-CoV-2 lineages circulating in Brazil.
Trial report in Nature communications, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 35 papers, 8 of them syntheses that pooled it.
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.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
35 citing papers in PubMed, 8 syntheses or guidelines pooled it, 54 citations in OpenAlex.
- Effectiveness of interventions to improve vaccine efficacy: a systematic review and meta-analysis.Systematic reviews · 2025Pooled it
- Comparative efficacy of leading COVID-19 vaccines: A network meta-analysis.The Indian journal of medical research · 2025Pooled it
- Assessing the robustness of COVID-19 vaccine efficacy trials: systematic review and meta-analysis, January 2023.Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin · 2023Pooled it
- Vaccine efficacy against SARS-CoV-2 for Pfizer BioNTech, Moderna, and AstraZeneca vaccines: a systematic review.Frontiers in public health · 2023Pooled it
- Efficacy and safety of COVID-19 vaccines.The Cochrane database of systematic reviews · 2022Pooled it
- COVID-19 vaccination efficacy in numbers including SARS-CoV-2 variants and age comparison: a meta-analysis of randomized clinical trials.Annals of clinical microbiology and antimicrobials · 2022Pooled it
- Effectiveness of COVID-19 vaccines against SARS-CoV-2 variants of concern: a systematic review and meta-analysis.BMC medicine · 2022Pooled it
- Real-Word Effectiveness of Global COVID-19 Vaccines Against SARS-CoV-2 Variants: A Systematic Review and Meta-Analysis.Frontiers in medicine · 2022Pooled it
- Effectiveness of ChAdOx1 nCoV-19 (Vaxzevria) primary series vaccine against SARS-CoV-2 beta and delta variants: a nationwide study.BMC infectious diseases · 2025Article
- Immunogenicity and Safety of ChAdOx1 nCoV-19 (AZD1222) as a Homologous Fourth-Dose Booster: A Substudy of the Phase 3 COV003 Trial in Brazil.Mayo Clinic proceedings. Innovations, quality & outcomes · 2025Article
- Humoral and cellular immune response to a single dose of a novel bivalent recombinant adenovirus-vector vaccine against West Nile virus and chikungunya virus in mice.Virology journal · 2025Article
- Vaccines for Respiratory Viruses-COVID and Beyond.Vaccines · 2024Review
- The effectiveness of booster vaccination of inactivated COVID-19 vaccines against susceptibility, infectiousness, and transmission of omicron BA.2 variant: a retrospective cohort study in Shenzhen, China.Frontiers in immunology · 2024Article
- Article
- Safety and incidence of COVID-19 following ChAdOx1(AZD1222) COVID-19 vaccination in Botswana.The Journal of infection · 2023Article
- An Attention towards the Prophylactic and Therapeutic Options of Phytochemicals for SARS-CoV-2: A Molecular Insight.Molecules (Basel, Switzerland) · 2023Review
- The current status of COVID-19 vaccines. A scoping review.Drug discovery today · 2022Article
- Effectiveness of COVID-19 Vaccination on Reduction of Hospitalizations and Deaths in Elderly Patients in Rio Grande do Norte, Brazil.International journal of environmental research and public health · 2022Article
- Persistence of immunity against Omicron BA.1 and BA.2 variants following homologous and heterologous COVID-19 booster vaccines in healthy adults after a two-dose AZD1222 vaccination.International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases · 2022Article
- Indoxyl Sulfate Alters the Humoral Response of the ChAdOx1 COVID-19 Vaccine in Hemodialysis Patients.Vaccines · 2022Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
30 authors at 17 institutions in 4 countries.
Funding
Abstract
Several COVID-19 vaccines have shown good efficacy in clinical trials, but there remains uncertainty about the efficacy of vaccines against different variants. Here, we investigate the efficacy of ChAdOx1 nCoV-19 (AZD1222) against symptomatic COVID-19 in a post-hoc exploratory analysis of a Phase 3 randomised trial in Brazil (trial registration ISRCTN89951424). Nose and throat swabs were tested by PCR in symptomatic participants. Sequencing and genotyping of swabs were performed to determine the lineages of SARS-CoV-2 circulating during the study. Protection against any symptomatic COVID-19 caused by the Zeta (P.2) variant was assessed in 153 cases with vaccine efficacy (VE) of 69% (95% CI 55, 78). 49 cases of B.1.1.28 occurred and VE was 73% (46, 86). The Gamma (P.1) variant arose later in the trial and fewer cases (N = 18) were available for analysis. VE was 64% (-2, 87). ChAdOx1 nCoV-19 provided 95% protection (95% CI 61%, 99%) against hospitalisation due to COVID-19. In summary, we report that ChAdOx1 nCoV-19 protects against emerging variants in Brazil despite the presence of the spike protein mutation E484K.
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What OpenQuestion holds
Registered trials
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.