If you are not scheduled for an appointment or having a difficult time getting one for you or a loved one. Believe it or not, many people scheduled to receive the vaccine are not showing up for their appointments. The Moderna, for example, has to be kept super cold. It's shelf life ,once removed from storage, is 6 hours. There are 10 doses in each vial. You can show up or check with your vaccine distributor in your area toward the end of the day to see if doses are going to be unused for that particular day. I see no problem, even if you don't fall into the category this time around, (under 65 etc.), if it means keeping a dose from being unused.