A few days ago, a doctor told an acquaintance of mine that, in light of the ongoing measles outbreak, he would never take an infant on an airplane. As a mother who plans to take her 7-month-old across the country next month, I was not pleased to hear his advice. My first reaction was: That’s insane! But, as nearly 1 out of every 3 children under the age of 5 who catches measles ends up in the hospital, how worried should parents of as-yet-unvaccinated infants be? And what can parents do, if anything, to keep their babies safe? Here are some answers.