Martha Ann Lillard, the last known American to rely on an iron lung after contracting polio, has died at the age of 78 in Shawnee, Oklahoma.

Lillard had lived inside the medical device, a negative-pressure ventilator that encloses a patient’s body except for the head and helps them breathe, since 1953, just two years before the polio vaccine became widely available in the U.S.

Polio, short for poliomyelitis, is a highly contagious virus that is primarily spread through contaminated food and water, as well as contact with unwashed hands or surfaces. Before vaccines eradicated the disease in the United States, outbreaks sparked widespread fear across the country.

The effective polio vaccine was developed by virologist and medical researcher Jonas Salk. In 1954, it went through one of the largest clinical trials involving nearly two million children and, in 1955, was declared "safe, effective, and potent." Salk's breakthrough saved countless lives, with cases plummeting 90% in two years.   

Lillard contracted the virus as a young child and became paralyzed in her arms and legs. She had to teach herself how to walk again and spent decades relying on the iron lung to help her breath. During healthier periods of her life, she was able to spend short periods of time outside the machine. 

The United States has been free of indigenous wild polio transmission since 1979. However, survivors like Lillard continued to live with the effects of the disease.