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

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.

Cited by papers we hold 22

• A critical overview of current progress for COVID-19: development of vaccines, antiviral drugs, and therapeutic antibodies · 2022
  No notice
• SARS-CoV-2 Mutations and Their Impact on Diagnostics, Therapeutics and Vaccines · 2022
  No notice
• SARS-COV-2 Variants: Differences and Potential of Immune Evasion · 2022
  No notice
• COVID-19 vaccine update: vaccine effectiveness, SARS-CoV-2 variants, boosters, adverse effects, and immune correlates of protection · 2022
  No notice
• COVID-19 Vaccination Hesitancy among Healthcare Workers—A Review · 2022
  No notice
• COVID-19 vaccine development: milestones, lessons and prospects · 2022
  No notice
• The Impact of Evolving SARS-CoV-2 Mutations and Variants on COVID-19 Vaccines · 2022
  No notice
• Effectiveness of COVID-19 vaccines against SARS-CoV-2 variants of concern: a systematic review and meta-analysis · 2022
  No notice
• Unadjuvanted intranasal spike vaccine elicits protective mucosal immunity against sarbecoviruses · 2022
  No notice
• Protective mucosal immunity against SARS-CoV-2 after heterologous systemic prime-mucosal boost immunization · 2021
  No notice
• Meta-Analysis and Structural Dynamics of the Emergence of Genetic Variants of SARS-CoV-2 · 2021
  Not checked
• Sex and Gender in COVID-19 Vaccine Research: Substantial Evidence Gaps Remain · 2021
  Not checked
• The effect of COVID-19 vaccination in Italy and perspectives for living with the virus · 2021
  Not checked
• Emerging SARS-CoV-2 Variants: A Review of Its Mutations, Its Implications and Vaccine Efficacy · 2021
  No notice
• COVID-19: Unmasking Emerging SARS-CoV-2 Variants, Vaccines and Therapeutic Strategies · 2021
  No notice
• Immune responses against SARS-CoV-2 variants after heterologous and homologous ChAdOx1 nCoV-19/BNT162b2 vaccination · 2021
  No notice
• Efficacy, Immunogenicity and Safety of COVID-19 Vaccines: A Systematic Review and Meta-Analysis · 2021
  No notice
• Impact of vaccination on new SARS-CoV-2 infections in the United Kingdom · 2021
  No notice
• The Disease Severity and Clinical Outcomes of the SARS-CoV-2 Variants of Concern · 2021
  No notice
• Distinguishing features of current COVID-19 vaccines: knowns and unknowns of antigen presentation and modes of action · 2021
  No notice

and 2 more

Reads

A person counts once a day per paper. We keep no cookie and no address: a reader is a hash that changes every day. Any month under five reads shows no number.