I apologize if I’m missing the point you’re making, but trench foot and vaccines are completely unrelated.

Vaccines fundamentally impact viruses. Trench foot is not caused by a virus, or any infection. It’s more akin to frostbite.

We’re really pushing the boundaries of what we can do with vaccines, but the root cause of trench foot is poor circulation, and a vaccine can’t really fix that.

I thought we are making cancer vaccines now. We are literally developing vaccines to fight thrombosis (aka blood circulation).[1] And we have vaccines that work against bacteria, specific toxins, parasites etc. Not sure you and I agree on what a vaccine is or does.

[1] https://www.ahajournals.org/doi/10.1161/HYPERTENSIONAHA.118....