[Comment] Polio vaccination: preparing for a change of routine
The Global Polio Eradication Initiative is on the brink of a major milestone. As of April, 2016, the serotype 2 component of oral poliovirus vaccine (OPV) will be removed from all immunisation activities worldwide. This transition, which is the first step in the synchronised withdrawal of all OPV serotypes, is essential to the polio endgame strategy. Although wild type 2 polioviruses have not caused a case of paralytic disease since 1999, vaccine viruses of this serotype have continued to cause rare cases of vaccine-associated paralytic poliomyelitis in OPV recipients or their close contacts,1 and sporadic emergences of circulating vaccine-derived polioviruses, wherein Sabin poliovirus strains mutate to regain neurovirulence.