Between 1953 and 1963 (1980 in Soviet countries) Polio vaccines of all types were raised in Green Monkey kidney cell cultures which unknown to workers were infected by the then unknown Simian Virus 40 which which we now know is a source of cancer in humans in later life - it may take decades to manifest.
As of 2018 Google Scholar has over 26,000 references between 2010 and 2018 for papers conducing research into this unknown contaminebt we injected into a large number of people. It's also implicated in the deactivation of Gene P53, which is dectivated in most cancer patients. Thus people that would probably never get polio anyway instead die of cancer caused by a polio vaccine that is now the only source of polio virus in the wild. There are now more lab strains of polio being found in people than wild strains of polio. In effect, we replaced the polio virus in the wild with a lab grown one and gave prople cancer in the process.
The rogue genes this injection added to some people opened up the field of dna viruses that cause cancer but this is hardly a silver lining.