Some mRNA vaccines encode not only the targeted protein antigen to elicit an immune response but also produce their own RNA-dependent RNA polymerase. Unknown possible risks of mRNA vaccines include type-1 interferon responses leading to inflammation and autoimmune conditions.

By contrast, the Oxford vaccine utilises a genetically re-programmed DNA adenovirus, one that produces only common cold symptoms, to express the coronavirus spike protein on the surface of itself.

Then the adenovirus modified not to replicate nor become infectious is injected as a vaccine to develop antibodies and immunological memory to fight the coronavirus with less risk of generating type-1 interferon response and autoimmunity as there is no mRNA lurking in our bodies.