COVID AND THE VACCINE - TRUTH, LIES, AND MISCONCEPTIONS REVEALED, page-99660

"How long do they keep for?"

I have some that I bought over 5 years ago and they are fine. Not sure of how long they can last. Depending on what one can read on the Internet (much of it fake) I would think it could be as much as 10 years, perhaps more. No need to be that long anyway. Just cycle through them and keep topping up the stock. The more interesting question is how long an emergency do you want to prepare for.