If you survived them before you must be immune.
When I served in the Navy over half-a-hundred years ago we were opening up a few inflatable lifecraft for inspection. They were provisioned with survival rations dated from during WWII. They were still edible. Not good, but hey, it’s just survival!
I got 4 Luckies in a little flip box, a couple of squares of TP and I think it was ham and eggs ... sort of
30 years later ... I didn't die and the cigarettes were still palatable
When I was stationed at Beale AFB in the 80’s I was tasked as a Shelter Commander. During one of our inspections of the shelter and supplies we found cases and cases of C-Rations stocked — all dated 1942. I could never get anyone to take my bet and eat one. LOL
Hey, C-rats were great! Well, some of them. I suspect if the balloon ever had gone up we'd have found shelters full of starved victims sitting on unopened crates of ham and lima beans, though.