Oxford/AstraZeneca COVID-19 Vaccine (ChAdOx1 nCoV-2019) Found Effective and Approved

Interim data from the phase III clinical trial of Oxford University/AstraZeneca COVID-19 Vaccine show the vaccine is effective at preventing COVID-19 caused due to SARS-CoV-2 virus and offers a high level of protection against the disease. 

The phase III trial tested two different dose regimens. The higher efficacy regimen used a halved first dose and standard second dose. The interim analysis indicated that efficiency was 90% in higher efficacy regimen and 62% in the other regimen with an overall efficiency of 70.4% when data from two dosing regimens were combined. Further, from those who received the vaccine, none progressed onto severe cases requiring hospitalisation (1).  

Upon analysis of the interim data, Medicines and Healthcare products Regulatory Agency (MHRA), the regulating body concluded that the vaccine has met its standards of safety, quality and effectiveness. The government has subsequently accepted the recommendation of MHRA and granted approval (2).  

Importantly, unlike earlier approved ‘COVID-19 mRNA vaccines’, this vaccine has relative advantage because can be stored at regular fridge temperature of 2-8 °C and can be distributed for administration at healthcare facilities using existing logistics thereby making it possible staple vaccine in the fight against the pandemic worldwide. However, mRNA vaccines have far wider potential in therapeutics and infections in the medium and long-term (3).   

Oxford/AstraZeneca COVID-19 Vaccine uses the weakened and genetically modified version of common cold virus adenovirus (a DNA virus) as vector for expression of viral protein of novel coronavirus nCoV-2019 in the human body. The expressed viral protein in turn act as antigen for development of active immunity. The adenovirus used is replication incompetent meaning it cannot replicate in human body but as vector it provides an opportunity for translation of incorporated gene encoding Spike protein (S) of novel coronavirus (1,4).  


Source (s):  

  1. Oxford University 2020. News – Oxford University breakthrough on global COVID-19 vaccine. Published 30 December 2020. Available online at Accessed on 30 December 2020.  
  1. MHRA, 2020. Medicines and Healthcare products Regulatory. Press release – Oxford University/AstraZeneca vaccine authorised by UK medicines regulator. Published 30 December 2020. Available online at Accessed on 30 December 2020. 
  1. Prasad U., 2020. COVID-19 mRNA Vaccine: A Milestone in Science and a Game Changer in Medicine. Scientific European. Available online at  
  1. Feng, L., Wang, Q., Shan, C. et al. 2020. An adenovirus-vectored COVID-19 vaccine confers protection from SARS-COV-2 challenge in rhesus macaques. Published: 21 August 2020. Nature Communications 11, 4207. DOI:  


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