I have periodic immunodeficiency for reasons no one can yet figure out, but I’m otherwise healthy. I try to be very careful about exposure but I still rely on a variety of antibiotics a few times a year to get over sinus infections, or more serious infections. I recently read a report by the CDC that says we will soon be living in a post-antibiotic age. What can I do? Move somewhere with low population density? Am I just doomed?