It began with a bad case of the flu. On September 30, James Talarico, the Democratic nominee for U.S. Senate in Texas, was supposed to sit down for an in-person interview with the Texas Hispanic Business Council. Instead, he moved it online and explained why: he had spent the night at an urgent care clinic in Dallas and had been diagnosed with influenza. It was an ordinary, human moment — the kind of minor health update that most politicians share and most voters forget. But in the hypercharged atmosphere of a midterm election, nothing stays ordinary for long. Within days,…

There was a time, not so long ago, when a child’s fever was enough to make parents’ hearts sink. A cough could turn into pneumonia, a stiff neck could be the first sign of meningitis, and a diagnosis of tuberculosis could change a family’s life forever. In the pediatric wards of that era, doctors and nurses saw children who were struggling to breathe, children whose brains were swelling with infection, and children who survived only to face permanent disabilities. It was a world that today’s young parents may find hard to imagine, thanks to one of the most powerful and…