Polio end game presentation

Editor's Notes

• #3: In this presentation, we will start with the current status of polio in the world and then in India, move onto the challenges in eradication of polio followed by GPEI/IAP guidelines for polio endgame strategy and lastly IPV as an effective tool in the eradication of polio.
• #4: Let us start with the current status of polio in the world and specifically in India.
• #5: It is interesting to know that there has been decrease in polio cases by over 99% since 1988, from an estimated 350 000 cases in more than 125 endemic countries then, to 650 reported cases in 2011. 1 In 2012, three countries, namely Nigeria, Pakistan and Afghanistan in the world remain endemic. 1 Reference 1. Poliomyelitis. Available at: http://www.who.int/mediacentre/factsheets/fs114/en/. Cited on May 7, 2013.
• #6: Though India is declared non-endemic, risk of importation still persists. 2002-2011 : 19 previously polio-free countries affected by WPV importations. Transmission of imported PV persisted for >12 months in 7 countries ( Angola, Chad, DR Congo , Eritrea, Djibouti, Ethiopia, Somalia) Importations caused large outbreaks >100 cases in 4 other countries (Yemen 478; Indonesia 299; Somalia 154; Sudan 146) China In Tajikistan, 452 WPV1 cases have been confirmed during January–June 2010. 1 In Afghanistan, poliovirus transmission has remained largely unchanged during 2009 to 2010. 11 WPV cases in 2009 and 10 WPV cases in 2010 were identifed. Two cVDPV2 cases have been identified in Afghanistan during 2009– 2010. 1 In India, 25 WPV cases (7 WPV1 and 18 WPV3) were identified during January–June 2010 as compared with 151 (28 WPV1, 122 WPV3, 1 mixed WPV1/WPV3) during January–June 2009. 1 The reduction in the number of WPV1 and WPV3 cases in India from 2009 signifies progress towards polio eradication. However, India is at moderate, decreasing risk of failure to detect and interrupt WPV transmission.  Reference 1. CDC assessment of risks to the global polio eradication initiative (GPEI) strategic plan 2010-2012. Available at:http://www.cdc.gov/vaccines/programs/global/downloads/gid-polio-risk-analysis-q2.pdf. Cited on May 5, 2013.
• #7: Let us now look at the status of polio in India. In 2009, India reported for nearly half the world’s polio cases. 1 The last polio case detected was on January As on 13 January 2013, India completes two years without any case of polio which marks an unprecedented progress in the eradication of polio. A major milestone achieved in the history of polio eradication is when India was declared non-endemic by the World Health Organization on February 25, 2012. 1 Reference  1. Polio Eradication. Available at http://www.unicef.org/india/health_3729.htm. Cited on May 7, 2013.
• #8: It is not really a time to celebrate, because To achieve WHO certification for Polio eradication, there should be no WPV case reported for 3 consecutive years i.e from 13-01-11 to 12-01-14. To achieve actual polio eradication, no polio, WPV, VDPV and VAPP cases should be reported.
• #9: Vaccine Derived Polio Virus are the derivatives of Sabin OPV strains exhibiting 1-15% divergence in the sequence of viral protein vp1 . Vaccine Derived Polio Virus origin from the accumulation of mutations by replication of the live vaccine strains within the vaccinee’s gut and recombination with other enteroviruses. They are potential to cause paralytic polio in humans and sustained circulation. Reference WHO. WER , 2006.
• #10: VDPV can cause sustained person-to-person spread and reintroduction of poliovirus. VDPVs are classified into 3 categories namely, circulating VDPVs, immunodeficient-associated VDPVs and ambiguous VDPVs. Circulating VDPVs emerge in areas with inadequate OPV coverage and may lead to sustained person-to-person spread. Immuno-deficient-associated VDPVs are isolated from persons with primary immunodeficiencies who exhibit prolonged VDPV infection after OPV exposure and are potential source of PV reintroduction in the future. They may excrete virus for up to 20 years. Ambiguous VDPVs are derived from clinical isolates from persons with no known immunodeficiency or environmental isolates with unidentified source. Reference 1.WHO . WER, 2006 2.McLennan et al. Lancet, 2000
• #11: This slide depicts the outbreaks of circulating VDPV.
• #12: Vaccine-Associated Paralytic Polio is defined as those cases of AFP from whose stool samples, vaccine-related poliovirus but no wild polio virus is isolated. It is caused by mutation of vaccine virus during replication in the gut of vaccinee (reversion to neurovirulence). VAPP is undistinguishable from naturally occurring polio. It has the same incubation period, range of severity and case fatality rate. It can affect both vaccinees & close contacts. References: Sutter et al. Vaccines , 2008. Paul. Vaccine , 2004. John. Bull of the WHO , 2004.
• #13: Global estimates of VAPP: WHO estimate: 250-500 cases / year (expressed as the number of cases per birth cohort) More realistic estimate: 400-800 Risk of VAPP increased by 2000-3200 fold in immunocompromised subjects  OPV contraindicated Increasing unacceptability of VAPP in countries where OPV is the major source of disease, especially at this stage of polio eradication: US 1980-98: 95% (144/152) of PP cases due to VAPP Prompted US and many countries to switch to full IPV-schedule Reference: 1. Introduction of inactivated poliovirus vaccine into oral poliovirus vaccine-using countries. Weekly epidemiological record .2003; 78:241–252. 2. Kohler KA, Banerjee K,Gary Hlady W, et al . Vaccine-associated paralytic poliomyelitis in India during 1999: decreased risk despite massive use of oral polio vaccine. Bulletin of the World Health Organization . 2002; 80 (3):210-216.
• #14: What are the threats and challenges faced in eradicating polio?
• #15: Although OPV is an effective tool for polio eradication, it is associated with rare cases of vaccine-associated paralytic polio (VAPP). There has increase in the use of tOPV doses through supplementary immunization activities , especially in UP and Bihar, since 2004. At the end of 2005, it was noted that the children in UP and Bihar received more doses of vaccine as compared to children in other parts of India. Children under 5 years old were reported to have received on average 15 doses of tOPV in UP and Bihar, compared with 10 in the rest of India, and only 4% of children were reported to have received fewer than 3 doses, of whom 90% were under 6 months old. It was reported that there was a decline in the relative odds of infection with paralytic polio with increasing number of doses of tOPV that is consistent with a constant, but unexpectedly low, probability of protection per dose. Hence, even 15 doses of OPV cannot provide immunity. Further, in low coverage populations, OPV viruses can evolve to become circulating vaccine-derived polioviruses ( cVDPVs) which may result in paralytic polio cases and outbreaks. 1 Reference: 1.Thompson KM, Tebbens RJD. Current polio global eradication and control policy options: perspectives from modeling and prerequisites for oral poliovirus vaccine cessation. Expert Rev Vaccines. 2012;11:449–459. 2.Grassly NC, et al. New Strategies for the Elimination of Polio from India. Science . 2006;314:1150-1153.
• #17: Merely eradicating WPV is not enough for the world to be called polio free. About 430 cases of VDPV have been reported worldwide between July 2009 and March 2011. In 2011, seven cases of VDPV were reported from India. 1 Virologists indicate that as long as OPV is used, the risk of VDPV causing polio in unprotected children persists. 1 Reference: 1.Verma R, Khanna P, Chawla S. Inactivated polio vaccine. Time to introduce it in India’s national immunization schedule. Hum Vacc Immunother. 2012;8:956–958.
• #18: Despite being declared non-endemic, the risk of polio still persists in India. Being in the neighbourhood of two polio endemic countries, Pakistan and Afghanistan, and significant international population movement, the risk of importation of polio from these countries cannot be ignored. Earlier, India has exported polio to other countries (Nepal, Tajikistan and Angola). There is a risk of import of poliovirus from the same routes. Since 2000, about 44 polio free countries have suffered from one or more importations of WPV. In order to avoid the cases of polio due to importation, maintenance of high population immunity, especially in the high-risk areas and among the most vulnerable population, is necessary. Maintaining high population immunity will help in preventing prevent importation of poliovirus as well as stop it from spreading, once imported. 1 Reference: 1.Key Messages:Avaiable at:www.unicef.org/ india /13_Jan_Breifing_note.doc . Cited on May 2, 2013.
• #19: Let us now look at the polio endgame strategy.
• #20: “ Polio endgame” refers to the management of post eradication risks of OPV. Type 2 cVDPV is the major post eradication concern. bOPV is better then tOPV and a possible option to replace it. Availability of low cost IPV may allow all countries to continue type 2 immunization, depending upon the need. 1 Reference: 1. A New Strategy for the ‘Polio Endgame’? Orientation for the SAGE IPV Working Group. 2011.Available at : http://www.who.int/immunization/sage/1_SAGE_IPV_WG_PolioEndgame_22Sept2011_nov11.pdf. Cited May 3, 2013.
• #21: Mere complete interruption of WPV transmission cannot make the world poliofree. Achieving a poliofree world will need cessation of all OPV and hence eliminate the risk of VAPP or VDPV infections. Transition from all OPV to sequential OPV-IPV and all IPV schedules has been implemented in several countries, in order to eliminate live poliovirus. 1 Reference: 1.Verma R, Khanna P, Chawla S. Inactivated polio vaccine. Time to introduce it in India’s national immunization schedule. Hum Vacc Immunother. 2012;8:956–958.
• #22: Since the launch of the Global Polio Eradication Initiative (GPEI) in 1988, a tremendous global effort to eradicate polio, the number of polio cases has declined by over 99% from an estimated 350 000 cases in 1988 to 650 reported cases in 2011. 1 Only 3 countries (Afghanistan, Nigeria and Pakistan) are now polio-endemic; down from more than 125 in 1988. 1 The number of wild polio virus (WPV) cases has significantly reduced in the previous two years. 2 References: Poliomyelitis. Fact sheet N°114. October 2012. Available at: http://www.who.int/mediacentre/factsheets/fs114/en/#. Cited May 3, 2013. Polio this week-As of 17 April 2013. Available at: http://www.polioeradication.org/Dataandmonitoring/Poliothisweek.aspx. Cited May 3, 2013.
• #23: In the post eradication era, when the OPV has to be stopped, but “vaccination against polio” cannot be stopped, IPV will play a very important role. 1 While OPV cessation is being implemented, IPV has emerged as a savior as it moderates the decline in population immunity, due to OPV cessation. 2 IPV offers complete individual protection and is an additional tool for those who can afford the vaccine. 1 Reference: Verma R, Khanna P, Chawla S. Inactivated polio vaccine. Time to introduce it in India’s national immunization schedule. Hum Vacc Immunother. 2012;8:956–958. Thompson KM, Tebbens RJD. Current polio global eradication and control policy options: perspectives from modeling and prerequisites for oral poliovirus vaccine cessation. Expert Rev Vaccines. 2012;11:449–459.
• #24: Risk of VAPP increases by 2000-3200 fold in immuno-compromised subjects and OPV contraindicated in such patients. In countries where only OPV is implemented, VAPP has become major source of disease, hence increasing its unacceptability. This prompted many countries to switch to full IPV-schedule. References: Atkinson. Pink Book , 2008 . WHO. WER , 2004. Jonh. Bull of the WHO , 2002. WHO. GPEI Strategic Plan 2004-2008. Available at: http://www.polioeradication.org/content/publications/2004stratplan.pdf, 2009.
• #25: After achieving the non-endemic status, in this post-eradication era, OPV needs to be discontinued but vaccination against polio cannot be stopped. Including IPV in vaccination schedules will avoid the issues such as VAPP. It is time to shift from OPV to IPV schedule in India. 1 Reference: 1.Verma R, Khanna P, Chawla S. Inactivated polio vaccine. Time to introduce it in India’s national immunization schedule. Hum Vacc Immunother. 2012;8:956–958.
• #26: High immunogenicity of IPV is reported in developing and tropical countries where OPV is suboptimal. High immunogenicity is also reported after 2 doses of IPV and immunogenicity is expectedly reinforced after 3rd dose of IPV. References 1. Polio Eradication Committee et al . Indian Pediatr , 2008. 2. Plotkin & Vidor. Vaccines .2008.
• #27: Inactivated polio vaccine is known to provide good herd effect. Excellent herd effect reported wherever IPV used on large scale in USA. References 1.John. Expert Rev Vaccines , 2009. 2.Stickle. Am J Public Health , 1954.
• #28: Herd immunity effect induced by IPV in the USA from 1958 to 1961.
• #32: This table represents the key attributes of OPV and IPV. OPV is produced from Sabin (attenuated) strains, where as IPV is produced from wild polio virus strains. Both OPV and IPV produce high systemic immunity. OPV produces high mucosal immunity whereas IPV produces lower mucosal immunity. High efficacy is reported with both OPV and IPV. But OPV confers suboptimal efficacy in tropical countries. Contact immunity is noted with OPV whereas contact immunity is not observed with IPV. Herd immunity is reported with both OPV and IPV. Risk of VAPP and VDPVs are reported with OPV whereas risk of VAPP and VDPV is not associated with IPV. OPV is contraindicated in immunodeficient individuals whereas IPV is the only polio vaccine recommended for immunodeficient individuals. Ease of administration (oral drops) but thermosensitive requiring efficient cold chain with use of OPV where administration of IPV requires skilled personnel for injection. OPV is the stand alone vaccine only, whereas IPV is available as stand alone and in combination vaccines. References Sutter, et al. Vaccines . 2008. Plotkin & Vidor . Vaccines . 2008.
• #33: What is the rationale for shifting to IPV? At present, it is becoming more and more apparent that long-term global eradication of poliovirus is impossible without IPV” Advantages of IPV are Safest polio vaccine that is there is no risk of VAPP/VDPVs. Only polio vaccine recommended to immunodeficient individuals IPV is reported to have high immunogenicity There is strong evidence of efficacy/effectiveness and Well-documented herd effect References: 1.Dutta. Vaccine , 2008. 2.WHO. WER , 2003. 3.Plotkin & Vidor . Vaccines , 2008.
• #34: The chief hurdle to shift from OPV to IPV is the cost. IPV is very costly, particularly among the low-income countries. Higher cost may pose further problem if type2 VDPV emerges during or immediately after the switch. In such a case, children immune to WPV1 and WPV3 will not be immune due to unaffordability of IPV. 1 Four possible ways to reduce the cost of IPV have been proposed. These include: 1 reducing the number of doses, using a fractional (1/5th) dose, increasing the interval between doses and producing the vaccine in resource-limited settings. Reference: 1.Ending polio: one type at a time. Available at: http://www.who.int/bulletin/volumes/90/7/12-020712/en/. Cited on:May 2 , 2013.
• #35: Let us now look at the IAP recommendations for IPV.
• #36: With the encouraging results of the GPEI and achievement of non-endemic status, IAP has taken the initiative towards the post-eradication preparation and adopted a sequential IPV-OPV schedule. 1 Introduction of sequential IPV-OPV will serve three purposes: It will help in adopting all-IPV schedule, and avoid risks associated with routine use of OPV (VAPP and cVDPVs). It will ensure parallel elimination of VDPV type 2 and eradication of last WPVs by switching from tOPV to bOPV in routine immunization. It will help in early introduction of IPV, particularly in high risk areas for VDPVs, to provide type 2 protection. Reference: 1.Indian Academy of Pediatrics Committee on Immunization. Consensus recommendations on immunization and IAP immunization timetable 2012. Indian Pediatrics. 2012;49:549–564.
• #37: The initial birth dose of OPV has been retained as recommended earlier since it is assumed that providing the first OPV dose at a time when the infant is still protected by maternally-derived antibodies may also prevent VAPP. In countries with high risk of poliovirus transmission, a birth dose of OPV is necessary. 1 The IAP recommendations for primary schedule includes: 1 Birth dose of OPV, Three primary doses of IPV at 6, 10 and 14 weeks, Two doses of OPV at 6 and 9 months, Booster dose of IPV at 15–18 months and OPV at 5 years. Alternatively, three doses of IPV can be used in the primary schedule at 8 and 16 weeks. While this schedule is immunologically superior to recommended schedule and uses lesser number of IPV doses, extra visits and incompatibilities with combining formulations may make it inconvenient. Moreover, there will be a risk of WPV in the first two months of life to a child. Reference: 1.Indian Academy of Pediatrics Committee on Immunization. Consensus recommendations on immunization and IAP immunization timetable 2012. Indian Pediatrics. 2012;49:549–564.
• #38: It is recommended that IPV should preferably be given intramuscularly or subcutaneously. It may be offered as a combination with other vaccines. It is recommended that in case of unaffordability or unavailability of IPV, the primary immunization schedule must be completed with three doses of OPV given at 6, 10, and 14 weeks. No child should be left without adequate protection against WPV. Also, all OPV doses (mono-, bi- or trivalent) offered through supplemental immunization activities, should be provided. Reference: Indian Academy of Pediatrics Committee on Immunization. Consensus recommendations on immunization and IAP immunization timetable 2012. Indian Pediatrics. 2012;49:549–564.
• #39: According to the IAP recommendations, in children less than 5 years of age, who have completed primary immunization with OPV, IPV may be offered as ‘catch up vaccination’. For the ‘catch up vaccination’ schedule, IPV can be given as three doses; two doses at two months interval followed by a third dose after 6 months. Such a schedule will ensure a long lasting protection against poliovirus. 1 Reference: 1.Indian Academy of Pediatrics Committee on Immunization. Consensus recommendations on immunization and IAP immunization timetable 2012. Indian Pediatrics. 2012;49:549–564.
• #40: Let us now discuss the barriers to polio eradication and the role of pediatricians in improving polio eradication process.
• #41: It has been well recognized that the best way to eradicate polio is to improve the routine immunization for complete coverage with polio vaccine. But, improving coverage is not as easy as it may appear. 1 References: 1.Choudhury P, Thacker N, Gargano LM, et al. Attitudes and perceptions of private pediatricians regarding polio immunization in India. Vaccine. 2011;29:8317–8322.
• #42: Since polio eradication has been challenging in India, a survey was conducted among pediatricians to identify the barriers to polio immunization in India. While most of the physicians considered polio eradication a priority, they identified several barriers that prevent complete coverage of polio vaccine. 1 Parents’ awareness and lack of confidence in polio vaccine were the two major hurdles. Religious beliefs, superstitions, cultural beliefs, fear of side effects and lack of time or priority were also identified as barriers to polio immunization. 1 References: 1.Choudhury P, Thacker N, Gargano LM, et al. Attitudes and perceptions of private pediatricians regarding polio immunization in India. Vaccine. 2011;29:8317–8322.