In discussing pros/cons of RNA and DNA based vaccines, that article says: "A DNA therapeutic, though, has to get into the nucleus to do anything, and that's yet another membrane to cross (and one with its own set of properties and gatekeepers). There's also the possibility for a DNA species to get mistakenly incorporated into a cell's own genome, which for a vaccine you don't want..."

So, I guess the J&J jab has that little potential problem.