Safety > Issues of Interest > Cancer
40 (SV40), Polio Vaccine, and Cancer
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What You Should Know
SV40 is a virus found in some species of
SV40 was discovered in 1960. Soon
afterward, the virus was found in polio vaccine.
Over 98 million Americans received
one or more doses of polio vaccine from 1955 to 1963 when a
proportion of vaccine was contaminated with SV40; it has been
estimated that 10 - 30 million Americans could have received
an SV40 contaminated dose of vaccine.
SV40 virus has been found in
certain types of cancer in humans, but it has not been determined
that SV40 causes these cancers.
The majority of scientific evidence
suggests that SV40-contaminated vaccine did not cause cancer;
however, some research results are conflicting and more studies
Polio vaccines being used today
do not contain SV40. All of the current evidence indicates that
polio vaccines have been free of SV40 since 1963.
In the 1950s, rhesus monkey kidney
cells, which contain SV40 if the animal is infected, were used
in preparing polio vaccines. Because SV40 was not discovered
until 1960, no one was aware in the 1950s that polio vaccine
could be contaminated.
SV40 was found in the injected
form of the polio vaccine (IPV), not the kind given by mouth
Not all doses of IPV were contaminated.
It has been estimated that 10-30 million people actually received
a vaccine that contained SV40.
- Some evidence suggests that receipt
of SV40-contaminated polio vaccine may increase risk of cancer.
However, the majority of studies done in the U.S. and Europe which
compare persons who received SV40-contaminated polio vaccine with
those who did not have shown no causal relationship between receipt
of SV40-contaminated polio vaccine and cancer.
For more information
- For more in-depth information about
SV40, polio vaccine, and cancer, see our frequently
- National Immunization Hotline:
English (800) 232-2522