As states expand covid-19 vaccine eligibility to allow shots for 16- and 17-year-olds, teens in rural America may have trouble getting them. Of the three vaccines authorized in the U.S., currently only one can go to that age group: the Pfizer-BioNTech shot. That vaccine comes in 1,170-dose packages at minimum and expires after five days in a fridge, meaning too many doses on too tight a deadline for many rural communities to manage.