Interestingly, if we were in an actual war, by law, Medicare doesn't cover war-related costs.
You can find this on the Medicare agency's public website, in a public-facing brochure call "Items and Services Not Covered Under Medicare," 18 pages, PDF here.
The original source for this is Social Security Act Section 1862(a)(5):
- Notwithstanding any other provision of this title, no payment may be made under part A or part B for any expenses incurred for items or services...which are required as a result of war, or of an act of war, occurring after the effective date of such individual’s current coverage under such part.
No one would invoke "the war against the virus" under this legal concept. But if, for example, North Korea dropped a bomb on Seattle as an Act of War, Medicare coverage wouldn't be available. (Such an event might lead to Congressional amendment, though).