Therefore, the claim that the definition of polio was chang…

Therefore, the claim that the definition of polio was changed to manipulate statistics appears to be unfounded based on the provided search results. **Note**: The actual criteria for diagnosing polio (including the duration of symptoms) may have evolved over time, but there is no evidence in the provided sources to support the specific claim of a change from 3 to 60 days post-Salk vaccine.