It depends on a few things. Maine requires one to use IMMPACT, so the inventory is there. It also depends if you lose power a lot. I won't go looking unless you do. Of course, I am sure it is the same with you as far as a plan of keeping the vaccines at the right temperature.
Of course, a generator will work.
But, there is this refrigerator that will keep the temperature the same for like 48 to 72 hours. But, as you would imagine, it is a bit pricey.
