An image carousel posted on social media promotes the myth that millions of Americans received polio vaccines contaminated with a cancer-causing SV40 virus.
The persistence of this misinformation increases its risk. Some early batches of the polio vaccine were contaminated with SV40. The virus can cause cancer in rodents, but there is no evidence that it causes cancer in humans. No polio vaccine administered since 1963 has contained SV40 contamination. Messaging may continue to emphasize key talking points: The polio vaccine is safe and the only way to eradicate polio.