> If you had the opportunity to save someone's life without any monetary reward, you would do it, right?
There are some people who think like this[1], but this is very much not a mainstream consensus. At the margin, "lives" in the general sense (not "lives of people close to you" or "lives in your country") cost about $5,000 to save. A marginal cost of $5,000 to save someone's life does not say to me "society highly values all human lives".
COVID vaccine distribution might well come in under that $5,000 / person mark -- looking at the data I see that neither Ethiopia nor Nigeria[2] has even received enough vaccine doses to vaccinate everyone over 65. So it seems plausible that fixing supply constraints could result in saving a few hundred thousand lives worldwide. As such, it might be worth it for some effective altruists to pitch in a couple of billion dollars to buy the rights from Moderna, if that would actually lead to a large enough supply increase to justify the expense.
What I don't think makes sense is trying to change the legal landscape after the fact to obtain a bunch of vaccine doses off of Moderna's research without compensating them for it. When there's a pandemic, we want vaccines. Setting a precedent that you can't make money solving a pandemic would be a really, really bad idea. We want the opposite precedent, because we want lots of people trying the next time something like this happens -- as such, the options on the table should be "buy a bunch of doses" or "buy out the rights to make your own, and the consultants who have the domain knowledge to make it happen, at a price which makes the prior research worthwhile in expectation", rather than "try to avoid paying enough to make the research worthwhile in order to save a couple billion dollars when responding to a pandemic that cost tens of trillions".
[1] https://www.givewell.org/
[2] as far as I can tell, every other country that reports such things has received enough doses, though that doesn't necessarily mean they used those doses on the people at highest risk