However, when three children became ill with paralytic polio following a dose of the vaccine, the directors of the Warm Springs Foundation in Georgia (acting as the primary funders for the project) requested it be withdrawn in December 1935. Following its withdrawal, the previously observed moratorium on human poliomyelitis vaccine development resumed and there would not be another attempt for nearly 20 years.While Brodie had arguably made the most progress in the pursuit of a poliovirus vaccine, he suffered the most significant career repercussions due to his status as a less widely known researcher. Modern researchers recognize that Brodie may well have developed an effective polio vaccine, however the basic science and technology of the time was insufficient to understand and utilize this breakthrough. Brodies work using formalin-inactivated virus would later become the basis for the Salk vaccine, but he would not live to see this success. Brodie was fired from his position within three months of the symposiums publication. While he was able to find another laboratory position, he died of a heart attack only three years later at age 36. By contrast, Park, who was believed in the community to be reaching senility at this point in his older age, was able to retire from his position with honors prior to his death in 1939. Kolmer, already an established and well respected researcher, returned to Temple University as a professor of medicine. Kolmer had a very productive career, receiving multiple awards, and publishing countless papers, articles, and textbooks up until his retirement in 1957.
Through continued study on an additional 26 monkeys, Brodie ultimately concluded that administration of live virus vaccine tended to result in humoral immunity while administration of killed virus vaccine tended to result in tissue immunity.Soon after, following a similar protocol to Kolmer, Brodie proceeded with self experimentation upon himself and his co-workers at the NYC Health Department laboratory. Brodies progress was eagerly covered by popular press as the public hoped for a successful vaccine to become available. Such reporting did not make mention of the 12 children in a New York City Asylum who were subjected to early safety trials. As none of the subjects experienced ill effects, Dr. Park, described by contemporaries as "never one to let grass grow under his feet," declared the vaccine safe. When a severe polio outbreak overwhelmed Kern County, California it became the first trial site for the new vaccine on very short notice. Between November 1934 - May 1935, over 1,500 doses of the vaccine were administered in Kern County. While initial results were very promising, insufficient staffing and poor protocol design left Brodie open to criticism when he published the California results in August 1935. Through private physicians, Brodie also conducted a broader field study, including 9,000 children who received the vaccine and 4,500 age- and location-matched controls who did not receive a vaccine. Again, results were promising. Of those who received the vaccine, only a few went on to develop polio.