In 1950s Hungary, with an economy and infrastructure still devastated from World War II and facing further hardships, thousands of children became permanently disabled and many died in the severe polio epidemic that shook the globe. The relatively new communist regime invested significantly in solving the public health crisis, initially importing a vaccine from the West and later turning to the East for a new solution. Through the history of polio vaccination in Hungary, this article shows how Cold War politics shaped vaccine evaluation and implementation in the 1950s. On the one hand, the threat of polio created a safe place for hitherto unprecedented, open cooperation among governments and scientific communities on the two sides of the Iron Curtain. On the other hand, Cold War rhetoric influenced scientific evaluation of vaccines, choices of disease prevention, and ultimately the eradication of polio.