In the early 20th century, polio was one of the most feared diseases in industrialized countries, paralyzing thousands of children every year. Soon after the introduction of effective vaccines in the 1950s and '60s, however, polio was brought under control and practically eliminated in these countries. It took somewhat longer for polio to be recognized as a major problem in developing countries.
While national immunization programs since the '70s have helped control the disease, the spread of polio was classified by the World Health Organization as a Public Health Emergency of International Concern (PHEIC) in January 2026, while the CDC issued a travel alert to US citizens, warning them of the risks of traveling without an up-to-date vaccine.
Click on for more about the history of polio and its current status.