In 2008 in San Diego, a 7-year-old boy whose parents refused vaccines contracted measles while on a family trip to Switzerland. Before realizing how sick he was, the boy went to school and infected four other kids at school, after having already infected his two siblings. He then infected four other children who happened to be in the waiting room at his pediatrician’s office. Three of those children were too young to have received their MMR vaccines. One of those infants was hospitalized; another traveled on an airplane while infectious. This case is a sobering example of how one family’s decision not to vaccinate their children has serious consequences for other children.

But it isn’t as sobering as the case in January in Minnesota in which an Hib meningitis outbreak severely sickened four children and killed one infant. Of those five children, one was too young to be vaccinated, one had an immune deficiency, and the other three had parents who refused the vaccine. The child who died was among those three children whose parents, out of fear or personal belief, opted out of the vaccine.