What vaccine safety concern did the IOM committee examine in the October 2002 report?
The committee reviewed the concern that SV40-contaminated polio vaccine could contribute to human cancers. Some of the polio vaccine given from 1955-1963 was contaminated with a virus called simian virus 40 (SV40). The virus occurs in some species of monkeys, though it does not typically cause illness in the animals. SV40 was discovered in 1960 and, soon after, it was identified in polio vaccine. It was found mostly in the injected, inactivated form of the vaccine (IPV), not the kind given by mouth (OPV). At that time, rhesus monkey kidney cells, which contain SV40 if the animal is infected, were used in preparing viral vaccines. Because SV40 was not discovered until 1960, no one was aware that polio vaccine made in the 1950s could be contaminated. In 1961, the virus was found to cause tumors in rodents. That same year, the federal government established testing requirements to verify that all new lots of polio vaccine are free of SV40. However, existing polio vaccine stocks were not r
