Polio Cases Peaked and Declined Three Years Before Vaccine Introduction

What was said

"The success story is that the US got polio vaccines in 1955, started rolling them out to first and second graders, and poof, polio was gone. only that ignores a very inconvenient timeline in that polio cases peaked in 1952 and began declining ever since. That was 3 years before the vaccine roll out. And importantly, polio diagnosis was changed at the same time."

Polio cases in the United States peaked in 1952 and were already in decline before the Salk vaccine rollout in 1955. Simultaneously, diagnostic criteria for polio changed in 1955, requiring observation 60 days apart instead of a single diagnosis upon paralysis presentation. This diagnostic change alone could account for decreased polio diagnoses independent of vaccine effectiveness, raising questions about how much credit the vaccine deserves for polio's decline.