Once drugs go off-patent, the subscription model is a lot less appealing. Even before then, allowing vaccines to sell for $200 per dose (I'm just making up this number) would encourage vaccine production. But you're right that this is an example of markets not doing the right thing, so it might take government, or even insurance company subsidies on vaccine development.

That’s not an outlandish number; retail price of the HPV vaccine in developed countries is about 200 euro a dose (though in practice usually paid by health services). They get a lot cheaper once out of patent, of course.

Permanently? I thought the standard of performance has become “reducing symptoms, maybe, we think, we’re not really sure. This is probably safe though”

True for anti-depressants. Evidence is extremely weak and the large majority of the effect in anyone below severe depression is known to be placebo.