Polio endemic countries hit all-time low of four.
D000346:Afghanistan / Q000453:epidemiology; D002648:Child; D003906:Developing Countries; D019353:Endemic Diseases; D014943:Global Health; D006801:Humans; D017589:Immunization Programs; D007194:India / Q000453:epidemiology; D009549:Nigeria / Q000453:epidemiology; D010154:Pakistan / Q000453:epidemiology; D011051:Poliomyelitis / Q000453:epidemiology / Q000517:prevention & control*; D023321:Poliovirus Vaccines / Q000008:administration & dosage*; D014944:World Health Organization
D023321:Poliovirus Vaccines