According to Wikipedia,
Louis Wendlin Sauer was an American pediatrician who became known for perfecting the vaccine used to prevent pertussis , saving countless lives around the world. After five years of work, Dr. Sauer developed the vaccine in 1931, inoculating children against pertussis, a respiratory infection that had been the most fatal disease for children under two years old. He later developed the DPT vaccine, which allowed the vaccines for diphtheria, pertussis and tetanus to be administered as a single injection. Dr. Sauer never asked for compensation for developing vaccines and told an interviewer later, "One doesn't do that thing for money."