Immunization Issues

SV40 Contamination of Polio Vaccine and Cancer

Updated: Enero 24, 2005

Some of the polio vaccine administered from 1955-1963 was unknowingly contaminated with a virus, called simian virus 40 (SV40).

The virus came from the monkey kidney cell cultures used to produce the vaccine. Because SV40 was not discovered until 1960, no one was aware that polio vaccine made in the 1950s could be contaminated.

It is estimated that over 98 million Americans received one or more doses of polio vaccine during the period of 1955-1963.

Most, but not all, of the contamination was in the inactivated polio vaccine (IPV). Once the contamination was recognized, steps were taken to eliminate it from future vaccines. No vaccines licensed for use in the US currently are contaminated with SV 40. What were the effects of the contaminated vaccine on the people who received it?

Although SV40 has biological properties consistent with a cancer-causing virus, it has not been conclusively established whether it has caused cancer in humans.

Epidemiological studies of groups of people who received polio vaccine during 1955-1963 do not show an increased cancer risk. However, a number of studies have found SV40 in certain forms of cancer in humans, such as mesotheliomas—rare tumors located in the lungs—brain, and bone tumors; the virus has also been found to be associated with some types of non-Hodgkin’s lymphoma.

In 2002, the IOM’s Immunization Safety Review Committee considered that the available data was inadequate to conclude whether or not the contaminated polio vaccine may have caused cancer.

Because there is biological evidence supporting the theory that SV40-contamination of polio vaccines could contribute to human cancers, the committee recommended continued public health attention in the form of policy analysis, communication, and targeted biological research.

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Further Studies

  • Engels EA, Chen J, Viscidi RP, et al (2004). Poliovirus Vaccination during Pregnancy, Maternal Seroconversion to Simian Virus 40, and Risk of Childhood Cancer. American Journal of Epidemiology, 160(4):306-316.
  • Rollison DE, Page WF, Crawford H, et al (2004). Case-Control Study of Cancer among US Army Veterans Exposed to Simian Virus 40-contaminated Adenovirus Vaccine. American Journal of Epidemiology, 160(4):317-324.
  • Engels EA, Switzer WM, Heneine W, et al (2004). Serologic Evidence for Exposure to Simian Virus 40 in North American Zoo Workers. The Journal of Infectious Diseases, 190:2065-2069.