Without specifically criticizing this vaccine process, I would add that if you start digging into medical research, you will find this is the rule rather than the exception. I've had my own semi-obscure issues I've gone trolling through the literature for assistance with, and one of the things I've found is that you'll find something that is tested; for a specific example, I found some examination of taurine supplementation for heart arrhythmia issues. There were multiple papers that all studied the exact same dosing schedule. This strongly suggests to me that the initial schedule was basically someone thinking for a moment and giving an informed guess about what might work.

This is just an observation, not a criticism, because I don't have a better suggestion for what they can do, nor do I particularly believe there is a much better suggestion necessarily. You have to start somewhere. My point is just that you shouldn't overestimate the exact numbers and how much effort was put into exploring all the details. Obviously some things are deeply studied, but most things won't be.

This implies that, statistically speaking, there very likely are drugs that were formulated, created, and put into a testing regime that they failed that actually work great, but were just dosed out to the study participants such that the good effects didn't emerge yet, or were dosed on a poor schedule, etc. (Or would have worked great if paired with a hit of grapefruit. [1]) I also wonder how that compares to the number of drugs that were never tested on humans because they failed animal testing, but it turns out that in reality they would have been fine in humans. Just idle musings on life.

[1]: https://news.ycombinator.com/item?id=24705855