[Pollard]

The technology was experimental before the pandemic, but has now been given to millions of people around the world.

Phase 4 trial included everyone that could be convinced/coerced to take it.

[exDemMom]

The purpose of a phase 4 trial is to keep studying a drug that has already received FDA approval. Sometimes, an adverse effect is so rare that it will not be observed in the phase 1, 2, or 3 trial populations. Adverse events in people receiving the drug are reported to the FDA, further investigation is done, and, if the FDA deems necessary, the drug is pulled from market. (Read about Vioxx.)

I will stress that any drug in phase 4 is NOT an experimental drug. Furthermore, any drug you are prescribed is, technically, a phase 4 drug.