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Cancer, Simian Virus 40 (SV40), and Polio
Vaccine Fact Sheet
- SV40 is a virus found in some species of
monkey.
- SV40 was discovered in 1960. Soon afterward,
the virus was found in polio vaccine.
- More than 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 are needed.
- 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.
Additional Facts
- 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
(OPV).
- 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.
More Information
- For in-depth information about SV40, polio
vaccine, and cancer, see our frequently
asked questions.
- National Immunization Hotline:
English 1 (800) 232-2522
Spanish 1 (800) 232-0233
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