Is it safe with regard to test efficacy to mail Binax rapid covid test kits (i.e. to a friend) in the winter when the weather is below freezing? The official instructions say to store at above 2 degrees C, but they are on sale on Amazon. Going to visit a friend in another city, being able to mail them a test for their use would be easier logistically than having them pick one up. I've tried googling this and found nothing, maybe somebody here knows.