[RWebb]

a lot of the time to vaccine is how safe you want it to be

you pointed out the post-chicken era we now live in, but that is for candidates

an actual vaccine goes thru 3 phases of trials (I'm sure you know this, but not everyone does)

IIRC, there are ~~ 70 being worked on with just a few in Phase I - from memory, no warranty expressed or implied...