The Oxford-AstraZeneca vaccine — and its Indian version Covishield from Serum Institute of India — is based on an adenovirus vector. That means it takes a safe version of a virus, and adds in the information from part of a pathogen, so that the body creates antibodies against this part of the pathogen. In the Covid-19 vaccine, the information it carries is about the SAR-CoV-2 spike protein. The idea is that when the real virus attacks, the antibodies will recognise and target it.
Obviously, the spikes developed as a result of vaccination are not the same as the spikes of the real coronavirus. But how similar are they?
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For the first time, new research has compared images of protein spikes — those on the surface of cells exposed to the Oxford-AstraZeneca vaccine, and the protein spike of SARS-CoV-2. The images show that the spikes are highly similar, the researchers have reported in the journal ACS Central Science. This supports the modified adenovirus used in the vaccine as a leading platform to combat Covid-19, they said.
In the study, scientists from the University of Oxford and the University of Southampton worked together to characterise the spikes manufactured by the cells presented with the Oxford-AstraZeneca vaccine. They exposed a range of cells in vitro to the vaccine. Using an imaging technique known as cryoEM, they took thousands of images which they then combined to build up a clear picture of the resulting protein spikes on the cells.
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Graphic depiction of the process of creating protein spikes on cells. (Source: University of Southampton)
Chemical analysis revealed that they bear a high resemblance to those surrounding the SARS-CoV-2 spikes.
The novel coronavirus SARS-CoV-2, yellow, emerging from the surface of cells, blue/pink, cultured in the lab. (NIAID-RML via AP, File) 
Graphic depiction of the process of creating protein spikes on cells. (Source: University of Southampton)
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