A 3y interval without cases in any member countries is what's required for the WHO to call a region "polio-free". [1] [1] - http://www.searo.who.int/immunizat

A 3y interval without cases in any member countries is what's required for the WHO to call a region "polio-free". [1] [1] - http://www.searo.who.int/immunization/topics/polio/eradication/sea-polio-free/en/ http://www.searo.who.int/immunization/topics/polio/eradicati...