27 feb 1979 año - Polio
Descripción:
Since 1979, no cases of Polio have originated in the United States. The virus though has been brought into the country by travelers; the last act of such occurring in 1993.(from https://www.cdc.gov)
Añadido al timeline:
fecha:
27 feb 1979 año
Ahora mismo
~ 45 years ago
