>>12829313J&J since:
1. adenoviral vaccines have been studied since the 50s-60s
2. large adenoviral vaccine clinical trials have already been done on different groups of people
3. J&J is using the tech it used in its ebola vaccine trial for corona and its its ebola trial went fine, years ago
Of course I'd just avoid vaccines altogether if I were a NEET or something since they're all a little premature, but I got the coworkers and the boss being all weird and I don't want them to accuse me of being anti vax. Honestly they all seem sage it's just that there isn't any long term data. But the J&J one seems the most "tried and true" technology.
