For decades, the Oral Polio Vaccine (OPV) has been the main tool used to eradicate polio. But at the end of 2012, global immunization experts made a landmark recommendation that every country in the world exclusively using OPV should add at least one dose of the inactivated polio vaccine (IPV) to their national immunization schedule by the end of 2015. This new policy meant that 126 countries around the world have to change their national immunization schedule within the short timeframe of only 3 years.
