Bureaucracy? This is the same type of go/no-go decision that R&D orgs have to make with incomplete information and immense costs every day. But with less complete information (no in-human data → 70-90% failure rate) and more immense costs (a couple hundred million dollars to get it through trials).

The problem is the cost and risk profile of drug development. With those parameters where they are, there will be countless "bureaucratic errors" of foregone opportunities, most of which we'll never even learn about.

Technically, they disappeared because of limited resources. If every pharmaceutical organization had unlimited funding to run unlimited trials, then they would.

How long do you have?

https://www.sciencenews.org/article/vaccine-beer-polyomaviru...