Simian Virus 40
Simian virus 40 (SV40) can cause cancer in animals. There is a small amount of evidence that this virus can infect humans, but there is no evidence that it causes health problems in humans. SV40 has no relationship to HIV or the simian immunodeficiency virus (the virus that causes AIDS in monkeys). In the early 1960s, some polio vaccines were discovered to contain SV40. Since 1961, manufacturers have been required to test for SV40. A few years later, manufacturers switched to species that do not harbor the virus. There is no evidence that polio vaccine produced since the early 1960s contained SV40.
So, people given polio vaccine between 1954 and 1962 in the U.S. (as many as 10 to 30 million) may have received SV40. Approximately 10,000 participants of clinical trials also may have received polio vaccine contaminated with SV40. However, studies in the U.S. have shown no increased rates of cancer for those given polio vaccine between 1954 and 1962. Also, studies in Sweden have not shown that people given vaccines possibly containing SV40 had a higher risk of cancer than those who were not exposed to these vaccines.
