> Then the medicine would need to be 100x [300x-400x] more expensive than the vaccine

I'm not suggesting this is true, but it would need to be 100x-400x more profitable, and that includes cost to make and store as well as the price is charged.

Maybe making mRNA vaccines costs much more than a simpler molecule like Paxlovid [0], and hospitals generally seem to charge much more than the over the counter price for everything. You've seen horror stories about $25 aspirin [1] which is easily 400x more expensive than the penny per pill cost of 500 tablets in a $5 bottle [2].

[0] https://en.wikipedia.org/wiki/Nirmatrelvir

[1] https://www.healthcarefinancenews.com/blog/why-aspirin-taken...

[2] https://amazon.com/Basic-Care-Aspirin-Regular-Strength/dp/B0...