POLICY Massachusetts broke ground on mandatory vaccination in 1905. History may repeat itself with COVID-19. by Stephen Ornes One spring morning in 1902, E. Edwin Spencer, the city physician of Cambridge, Massachusetts, visited the home of Henning Jacobson, a local Lutheran preacher. Spencer had the vaccination for smallpox. Jacobson refused it for both himself and his family. The standoff between the two men would lead to what historian Michael Willrich called “the seminal case in modern American public health law.” The Boston area was then experiencing what would be its last smallpox epidemic, which killed approximately 270 people over three years. At the time, smallpox—a highly contagious virus—was a leading cause of death around the world. Victims were diagnosed by telltale pustules, and during some outbreaks, as many as one in three infected people died.