1) There’s no way the public would buy in to this idea. 2) This seems like a serious violation of medical ethics. 3) If we already gave a well-engineered and safe vaccine, why not take that? Supply chain and immunization itself isn’t a practical choke point: it’s vaccine accuracy for things like flu, and vaccine misinformation for something like measles. But again, take the vaccine or don’t: for most illnesses and most scenarios, you’re only hurting yourself.