Immunization against poliomyelitis: still problems to solve in both developed and developing countries.
D003906:Developing Countries; D006801:Humans; D007117:Immunization, Secondary; D011051:Poliomyelitis / Q000517:prevention & control*; D011055:Poliovirus Vaccine, Oral / Q000627:therapeutic use; D014611:Vaccination / Q000191:economics
D011055:Poliovirus Vaccine, Oral