Polio this week as of 28 October 2015
On 20 October, the Strategic Advisory Group of Experts on immunization (SAGE) confirmed that the globally coordinated withdrawal of the type 2 component in oral polio vaccine (OPV) should occur in April 2016, specifically in a window from 17 April to 1 May. Countries should intensify their preparatory efforts to switch from trivalent OPV to bivalent OPV to meet this timeline.
Withdrawing OPV type 2 is a crucial part of the polio endgame strategy, in order to eliminate the very rare cases of vaccine associated paralytic polio (VAPP) or circulating vaccine derived polioviruses (cVDPVs). The type 2 component of OPV accounts for 40% of VAPP cases, and upwards of 90% of cVDPV cases. By contrast, wild poliovirus type 2 has not been detected anywhere since 1999 and the Global Commission for the Certification of Poliomyelitis Eradication (GCC) declared this strain globally eradicated at its meeting in September 2015.
SAGE cautioned, however, that more work needs to be implemented ahead of the April 2016 switch date. It is critical that countries meet established deadlines to protect populations by moving the world towards destruction of wild poliovirus type 2 stocks or their appropriate containment in designated ‘poliovirus essential’ facilities. Ongoing cVDPV2 outbreaks needed to be fully stopped. And a global supply constraint of inactivated polio vaccine needed to be carefully managed in the lead-up to the switch, with available supply prioritized to highest risk areas.