lives. >> you're a good baby. >> reporter: pediatrician andy margileth is 101, but shows no sign of slowing down. >> it's a feel-good job. it's not even a job. it's just fun. >> cute! >> reporter: dr. andy, as he is known, is one of only a dozen century-old doctors in the u.s. still practicing today. >> what is more important than helping other people? >> reporter: the world war ii navy veteran had an award named after him for his work in military pediatrics. he has practiced long enough to know what is it like long before vaccines protected us. long before covid, another virus was especially lethal for children. >> polio was so bad, the death rate, the kids who were getting into the iron lung, it was awful. >> reporter: back then, dr. andy was on the cutting edge of vaccine development and cures for childhood disease. >> we gave the kid one dose, and the leukemia was gone. this is called gratification. it's cheating to sit down. >> reporter: it's that lifetime of service to his country and his patients that sustains him. >> if you had to put a headline on this thing, i guess you'd