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Vaccine contamination with Simian vacuolating virus 40, known as SV40 occurred in the United States and other countries between 1955 and 1961. SV40 is a monkey virus that has the potential to cause cancer in animals and humans, although this is considered very unlikely and there have been no known human cases. [1]
The hypothesis that SV40 might cause cancer in humans was a particularly controversial area of research, fuelled by the historical contamination of some batches of polio vaccine with SV40 in the 1950s and 1960s. [4] "Persuasive evidence now indicates that SV40 is causing infections in humans today and represents an emerging pathogen."
However, a 1999 study is among those that find that "increased incidence of certain cancers among the 98 million persons exposed to contaminated polio vaccine in the U.S." [22] The question of whether SV40 causes cancer in humans remains controversial, however, and the development of improved assays for detection of SV40 in human tissues will ...
The polio vaccine has all but obliterated the illness that once killed thousands and paralyzed 15,000 people nationwide every year. ... is a distinctly contagious illness caused by a virus called ...
By 1961, only 161 cases of polio were documented. Before the vaccine, the disease had been a major cause of disability in children, according to theMayo Clinic. Several polio epidemics occurred ...
Before vaccines were available in 1955, polio caused 15,000 cases of paralysis in the US each year. The US eliminated the disease in 1979, but unvaccinated travelers can still carry polio in.
There are two kinds of polio vaccine—oral polio vaccine (OPV), which uses weakened poliovirus, and inactivated polio vaccine (IPV), which is injected. OPV is less expensive and easier to administer, and can spread immunity beyond the person vaccinated, creating contact immunity. It has been the predominant vaccine used.
Two vaccines are used throughout the world to combat poliomyelitis.The first, a polio vaccine developed by Jonas Salk, is an inactivated poliovirus vaccine (IPV), consisting of a mixture of three wild, virulent strains of poliovirus, grown in a type of monkey kidney tissue culture (Vero cell line), and made noninfectious by formaldehyde treatment.