Suffer the Children by Craig DiLouie

During the initial outbreak of “Herod's Syndrome,” all prepubescent children suddenly drop dead at about the same time. Grief, despair, and unreality encompass parents while funeral homes  struggle to keep up with so many dead all at once. Three days later, after many are buried and rotting, all the children suddenly wake up with no memory of what has happened. All seems oddly normal, until they start to die again. At the unsettling request of the children, the parents learn that once given blood, the children return to their normal state for a short period of time. One and a half pints seem to give a child about three hours of life before they die again. The real horror of the story comes from the desperation of parents to keep their children alive. How far will a parent go to save their child?