Martha Lillard had just turned 5 when she was diagnosed with polio and depended on an iron lung to live. She died June 26 in Oklahoma, the last U.S. polio patient who used the machine, her sister said. She was 78. "They told her she wasn't supposed to live past 20 years old," Lillard's younger sister, Cindy McVey, told The Associated Press on Friday. "She had the enthusiasm and the drive to continue living and make the best of her life." McVey attributes her sister's death to the effects of long Covid. A death certificate lists causes as chronic pulmonary failure and post-polio syndrome, McVey said.