Even if you limit yourself to considering only currently living humans, calculating the cost of preventing deaths is almost universally avoided by government policy makers of any sort.
Even worse is considering the cost per healthy life year. It's very rare to find any policy maker even willing to discuss this. One that have seen is Britain's NHS, who will spend £20,000 - £30,000 to give cancer patients 1 extra "Quality adjusted life year"[1]. But this is only used to compare drug prices and never mentioned even in the context of other UK government health interventions, which might have a much higher cost (e.g. COVID measures which might have cost 100x more per Qaly) or much lower (e.g. teen mental health might cost 100x less per Qaly). And that's just discussing health care inside a single country. The cost per Qaly of foreign aid to areas experiencing famine might be 10,000x lower than other policies.