Vaxzevria – Oxford-AstraZeneca vaccine

How does Vaxzevria, the Oxford-AstraZeneca COVID-19 vaccine work?


The Oxford-AstraZeneca vaccine is made from a virus (ChAdOx1), which is a weakened version of a common cold virus (adenovirus) that causes infections in chimpanzees. The adenovirus has been genetically changed so that it is impossible for it to cause infection in humans.

Genetic material has been added to this weakened adenovirus, allowing it to make spike proteins from the COVID-19 coronavirus (SARS-CoV-2). These proteins are found on the surface of SARS-CoV-2, the virus that causes COVID-19. They play an essential role in the infection pathway of the SARS-CoV-2 virus.

Vaccinating with this weakened adenovirus, trains the body to recognize SARS-CoV-2 virus and develop an immune response to its spike protein that helps to prevent disease if SARS-CoV-2 virus later enters the body.

COVID-19 vector vaccines:

  • are made from a weakened, harmless virus that mimics the COVID-19 virus
  • train the body to recognize the spike protein of SARS-CoV-2 virus
  • prevent COVID-19 disease