Celine Gounder

Rahima Banu, a toddler in rural Bangladesh, was the last person in the world to contract variola major, the deadly form of smallpox, through natural infection. In October 1975, after World Health Organization epidemiologists learned of her infection, health workers vaccinated those around her, putting an end to variola major transmission around the world. The WHO officially declared smallpox eradicated in 1980, and it remains the only human infectious disease ever to have been eradicated.

In late May of 2020, the U.S. hit one of what has become so many grim pandemic milestones: our first 100,000 dead from COVID-19. I remember how heartbroken I was then—and how frustrated. The novel coronavirus, a stealthy pathogen, was bound to take a toll no matter how perfect Americans’ response was to the crisis. But Americans’ response was far from perfect. I was frustrated by people who refused to wear a mask.