"vaccine-derived poliovirus" what the WHO calls What is vaccine-derived polio? vaccine "What is vaccine-derived polio?" het virus in het vaccin muteert They stated What is vaccine-derived polio? puede 'contagiarse' Oral Polio Vaccine (OPV) WHO explains fewer than 760 cases more than 10 billion doses of OPV http://www.who.int/features/qa... 24 outbreaks of cVDPV have occurred writes What is vaccine-derived polio? http://www.who.int/features/qa/64/en/ vaccine http://www.who.int/features/qa/64/en/ what the WHO calls writes http://www.who.int/features/qa/64/en/ http://www.who.int/features/qa/64/en/ fewer than 760 vaccine-derived poliovirus what the WHO calls What is vaccine-derived polio? VDPV 760 cases of VDPV vaccine They stated retiré de la circulation par précaution WHO writes WHO explains http://www.who.int/features/qa/64/en/ WHO vaccine-derived polio What is vaccine-derived polio? Was ist ein vakzin-abgeleitetes Poliovirus? http://www.who.int/features/qa/64/en/ hundreds of millions poliovirus derivado de la vacuna vaccine-derived poliovirus WHO explains WHO explains What is vaccine-derived polio? fewer than 760 cases http://www.who.int/features/qa/64/en/ originating from poliovírustipo 2 World Health Organization more than 10 billion doses of OPV vaccine-derived poliovirus