Staying polio-free
Overview
Keeping the South-East Asia Region Polio-free
What are the main new developments since regional polio-free certification?
Immunization
There are three types of wild poliovirus - type 1, 2 and 3 - each of which targeted by a different component of the trivalent oral poliovirus vaccine (tOPV). Live attenuated vaccines are very effective against the wild virus, but in very rare cases can lead to paralysis. Circulating vaccine derived poliovirus (cVDPV) outbreaks are rare occurrences when a vaccine-related virus is passed from person-to-person, mutating over time and acquiring wild virus transmissibility and neurovirulence characteristics. Almost all cVDPV outbreaks in recent years have been caused by a type 2 vaccine-derived virus. Wild poliovirus type 2 was last detected in 1999 and was officially declared as globally eradicated by the Global Certification Commission in September 2015. Therefore, OPV type 2 carried more risk than benefit and thus undermining global polio eradication efforts. Subsequently, tOPV has been replaced with bivalent OPV (bOPV), which will continue to target the remaining polio types 1 and 3. Once these types are eradicated, bOPV will also be withdrawn.
There are three types of wild poliovirus - type 1, 2 and 3 - each of which targeted by a different component of the trivalent oral poliovirus vaccine (tOPV). Live attenuated vaccines are very effective against the wild virus, but in very rare cases can lead to paralysis. Circulating vaccine derived poliovirus (cVDPV) outbreaks are rare occurrences when a vaccine-related virus is passed from person-to-person, mutating over time and acquiring wild virus transmissibility and neurovirulence characteristics. Almost all cVDPV outbreaks in recent years have been caused by a type 2 vaccine-derived virus. Wild poliovirus type 2 was last detected in 1999 and was officially declared as globally eradicated by the Global Certification Commission in September 2015. Therefore, OPV type 2 carried more risk than benefit and thus undermining global polio eradication efforts. Subsequently, tOPV has been replaced with bivalent OPV (bOPV), which will continue to target the remaining polio types 1 and 3. Once these types are eradicated, bOPV will also be withdrawn.
Surveillance
Nationwide acute flaccid paralysis (AFP)) surveillance remains the gold standard for detecting polio cases. The four main steps of surveillance are i) finding and reporting children with AFP; ii) collecting and transporting stool samples for analysis; iii) isolating and identifying poliovirus in the laboratory and iv) classifying AFP cases. Quality standards for each step have been established and are being monitored by the Regional Certification Commission for Polio Eradication. Accreditation visits reaffirm that the polio laboratories in the regional network have updated standard operating procedures for safe handling of AFP specimens and viral isolates in place and are meeting the global benchmarks for poliovirus diagnostics.
Environmental surveillance involves testing sewage or other environmental samples for the presence of poliovirus and complements clinical surveillance for possible polio cases. Environmental surveillance often confirms poliovirus infections in the absence of cases of paralysis. As such, environmental surveillance in the Region has been expanded to include additional sites in Indonesia and India and to initiate surveillance in Thailand, Bangladesh, Myanmar and Nepal. Over 80 sites in these 6 countries are now conducting environmental surveillance. Data provided important evidence for the disappearance of Sabin-like poliovirus type 2 following the switch from tOPV to bOPV in 2016 and continue to guide investigations and responses to VDPVs detected in sewage samples or the general population.
Certification
The Regional Certification Commission for Polio Eradication (RCCPE)– together with National Certification Committees for Polio Eradication (NCCPEs) – is part of a three-tiered global structure headed by the Global Certification Commission (GCC) which provides a framework of independent bodies to assist the Global Polio Eradication Initiative (GPEI) in certifying and maintaining polio eradication in a standardized, ongoing, and credible manner. Their members meet regularly to comprehensively review population immunity, surveillance, laboratory containment and other data to assess the status of polio eradication and/or maintaining polio-free status.
The first regional polio certification body - at that time called the “International Certification Commission for Polio Eradication in the South-East Asia Region (ICCPE)” - was appointed by the WHO Regional Director in January 1997 and the first ICCPE took place in New Delhi, India in June 1997; followed by seven more meetings in subsequent years. In 2008 the commission was restructured to the RCCPE and had its first meeting in December 2008 in New Delhi India. Following 24 months of great progress towards polio eradication and with the last case of wild poliovirus in the Region was reported from India on 13 January 2011, the RCCPE geared up its work to re-energize and reinvigorate certification efforts and met three times in 2012 and twice in 2013 to scrutinize evidence from all countries if indeed poliovirus transmission had been interrupted.
Since regional certification on 27 March 2014, the RCCPE has updated its terms of reference and working procedures to monitoring maintaining the polio-free status and meeting requirements of the Polio Eradication and Endgame Strategic Plan, the comprehensive framework developed by the GPEI to deliver a polio-free world.
The Polio Endgame Strategy 2019-2023
