Wouldn’t stomach acid tear the antigens up?
I work with, among others, natural polymers and depolymerization has been the bane of my existence for the last 20 years. pH extremes only make it worse.
One problem with relying on stomach acid- digestion starts in the mouth. They’ve been able to make selective vaccines for years. They’re also able to add and remove a number tag on one’s DNA. A lot of science has been made more public thanks to the Covid fiasco.