The Johnson and Johnson and the AstraZeneca vaccines contain in them a vital ingredient known as Adenovirus. This is because the adeno-virus based components helps to expel the covid spike protein produced by the virus that has the ability to replicate and harm the cells of humans.
The Adenovirus contains 30-40 separate genes that code for different protein and they're grouped into two categories: proteins from the early genes and later genes. The early genes produces E1 to E4. The virus quickly produces E1 and once E1 is functional, the other E series that's helps produce spike proteins will quickly replicate. The Johnson and Johnson and AstraZeneca vaccines during production deleted E1 from the virus DNA and also deleted E3 because they're no longer needed since E1 has been deleted.
Once they deleted E1 they replaced it with DNA for SARS-CoV-2 or covid spike protein. E4 is modified to allow the vaccine work better.
Finally, the inclusion of adenovirus based components in the above mentioned two vaccines gives it a far better way of fighting the coronavirus. Although we all know the side effects of the AstraZeneca vaccine which is majorly blood clot.