This resulted in the APHA arranging a Symposium on Poliomyelitis to be delivered at the Annual Meeting of their Southern Branch the following month. It was during the discussion at this meeting that Dr. James Leake of the U.S. Public Health Service stood to immediately present clinical evidence that the Kolmer vaccine had caused several deaths and then allegedly accused Kolmer of being a murderer. As Rivers recalled in his oral history, "All hell broke loose, and it seemed as if everybody was trying to talk at the same time....Jimmy Leake used the strongest language that I have ever heard used at a scientific meeting." In response to the attacks from all sides, Brodie was reported to have stood up and stated, "It looks as though, according to Dr. Rivers, my vaccine is no good, and, according to Dr. Leake, Dr Kolmers is dangerous." Kolmer simply responded by stating, "Gentlemen, this is one time I wish the floor would open up and swallow me." Ultimately, Kolmers live vaccine was undoubtedly shown to be dangerous and had already been withdrawn in September 1935 prior to the Milwaukee meeting. While the consensus of the symposium was largely sceptical of the efficacy of Brodies vaccine, its safety was not in question and the recommendation was for a much larger well-controlled trial.
With wild polio cases at record lows, 2017 was the first year where more cases of cVDPV were recorded than the wild poliovirus, a trend that is expected to continue.To combat this, the WHO in 2016, decided to switch from the trivalent polio vaccine to the bivalent polio vaccine. This vaccine no longer contains the type 2 polio virus because it was eradicated in 1999. Contamination concerns
In 1960, the rhesus monkey kidney cells used to prepare the poliovirus vaccines were determined to be infected with the simian virus-40 (SV40), which was also discovered in 1960 and is a naturally occurring virus that infects monkeys. In 1961, SV40 was found to cause tumors in rodents. More recently, the virus was found in certain forms of cancer in humans, for instance brain and bone tumors, pleural and peritoneal mesothelioma, and some types of non-Hodgkin lymphoma. However, SV40 has not been determined to cause these cancers.SV40 was found to be present in stocks of the injected form of the IPV in use between 1955 and 1963. It is not found in the OPV form. Over 98 million Americans received one or more doses of polio vaccine between 1955 and 1963 when a proportion of vaccine was contaminated with SV40; an estimated 10–30 million Americans may have received a dose of vaccine contaminated with SV40.