I'm not suggesting to include new strains on the fly while they are discovered without trials. The same way they had to do trials for Gardasil-9 after already having Gardasil, they could do the same just with a wider cocktail.

In the optimal case you would attempt the 100+ cocktail and don't have any unreasonable side effects from them. Of course if there is a single variant in there that causes side effects you would need a ton of trials to triangulate which one causes them, but there is no guarantee that that is necessary or that you wouldn't run into that variant when you just adding 5 new variants in an iteration.

Do you have a reference for this? It was my assumption too, reading about the Pandemrix vaccine, but I didn’t find any dependable references for this.

Even if he is wrong about how it works, because of the potential for unknowns they need to study it in a trial. There is a lot we don't know about biology.