The big problem with the Oxford ChAdOx1 nCoV-19 vaccine that I haven't seen discussed much is that it doesn't seem to work very well.

Viral gRNA was detected in nose swabs from all animals and no difference in viral load in nose swabs was found on any days between vaccinated and control animals

https://www.biorxiv.org/content/10.1101/2020.05.13.093195v1

For a less technical write-up: https://www.forbes.com/sites/williamhaseltine/2020/05/16/did...