On this day in 1953, Dr. Jonas Salk reported successfully testing a vaccine against polio. Within a few months, the Salk vaccine was formally approved for preventing infantile paralysis. A far-reaching program of child inoculation began in the US.

A History Moment. Polio has probably caused paralysis and death for most of human history. The oldest reference to it is a 3,000 year old Egyptian engraving. Oddly, cases of polio were rare in ancient times because sanitation was generally poor.

Better Sanitation, More Polio? With improvements in waste disposal and the use of indoor plumbing in the 20th century, epidemics of polio became more common, especially in cities during the summer.

No Immunity. With sewage being dumped away from the drinking water supply, babies were less likely to be infected with polio and become immune to it. But when the children got older, playing with others, swimming in public pools, and going to school, they were more likely to be exposed to the virus. And that form of the virus was more likely to cause paralytic poliomyelitis, a form of polio that causes paralysis.

Most Feared Disease. By the time of the Great Depression, paralytic polio was perhaps the most feared disease. It struck fast, there was no cure, and its victims were crippled for life. They spent the rest of their days on crutches, in wheelchairs, or lying immobile in giant iron lungs.

FDR Fights Back. President Franklin Delano Roosevelt, himself a Polio victim, declared a war on Polio during his administration. The resources of postwar America went to work on a cure.

What's the Salk Vaccine? In the early 1960s, the work paid off, first with the Salk vaccine, and soon after with the Sabin virus strains. Salk used chemical and heat treatment to kill poliovirus, then injected the inactivated virus into patients. The proteins of the destroyed virus "taught" the patients' immune systems to recognize polio, protecting them against it.