Many years ago, measles was almost commonplace. Millions of people every year caught the virus. It was very common among children, and while not ordinarily deadly, cases were severe enough for worldwide concern. But everything changed in the early 1960s when the measles vaccine was invented. Almost overnight, the virus disappeared, and cases dropped annually to just hundreds. And while it’s still possible to catch the virus, it’s not usually a big deal. However, a recent outbreak in rural Texas has caused the medical world to be very concerned. Hundreds of people are spreading the virus, and the numbers keep growing…