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Ipv – need of the hour   dr gaurav gupta
 

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Injectable Polio Vaccine in Indian Context, presented on 11th Dec 2011 at Haryana State Pediatric Conference, Kurukshetra on 11th Dec, 2011

Injectable Polio Vaccine in Indian Context, presented on 11th Dec 2011 at Haryana State Pediatric Conference, Kurukshetra on 11th Dec, 2011

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    Ipv – need of the hour   dr gaurav gupta Ipv – need of the hour dr gaurav gupta Presentation Transcript

    • IPV – Need of the hour Dr Gaurav Gupta Pediatrician, Charak Clinics, Mohali [email_address]
    • A brief history of Polio
      • First described by Michael Underwood in 1789
      • First outbreak described in U.S. in 1843
      • 21,000 paralytic cases reported in the U. S. in 1952
      • Global eradication in near future
    • A brief history of Polio Vaccine
      • 1955 Inactivated vaccine
      • 1961 Types 1 and 2 monovalent OPV
      • 1962 Type 3 monovalent OPV
      • 1963 Trivalent OPV
      • 1987 Enhanced-potency IPV (eIPV)
    • Summary of Key Attributes of OPV and IPV Adapted from 1, 11 Sutter et al. Vaccines , 2008 Plotkin & Vidor . Vaccines , 2008
    • Despite Significant Progress, 4 Countries Still Remain Endemic for Polio WHO. Poliomyelitis Fact sheet. Available at: http://www.who.int/mediacentre/factsheets/fs114/en/print.html , 2009 WHO. Polio Case Count. Available at: http://www.who.int/immunization_monitoring/en/diseases/poliomyelitis/case_count.cfm , 2009 Graph adapted from WHO. Progress Towards Global Immunization Goals. Available at: http://www.who.int/immunization_monitoring/data/SlidesGlobalImmunization.pdf , 2009 Polio Eradication Progress, 1988-2008
      • 1988 : 350,000 estimated cases
      • >125 endemic countries
      • 2008 : 1,652 cases
      • 4 endemic countries
        • India, Nigeria, Afghanistan, Pakistan
      Endemic with wild polio virus (4 Countries) Certified polio-free regions (114 countries) Not certified but non-endemic (73 countries)
    • Polio Eradication: A Godzilla of Campaigns
      • Just think…..
      • In 2008, India administered more than one billion doses of OPV during polio vaccination campaigns.
      • On any given National Immunization Day (NID), more than 72 million children were immunized across a single weekend, making these regular occurrences repeatedly the largest immunizations in history !
      • And somewhere in India, polio campaigns were conducted in 24 out of the 52 weeks in the year.
    • Weekly AFP and VPD Update for Week 48, 2011 Data as of 05 December 2011
    • Wild Polio Virus India, 2010 *Dots are randomly placed within blocks (Sub-districts) Data as of 05 Dec 2011 Districts with cases in 2010 = Most recent P3 Wild polio case = Most recent P1 Wild polio case
    • Wild Polio Virus India, 2011 *Dots are randomly placed within blocks (Sub-districts) Data as of 05 Dec 2011 = Most recent P1 Wild polio case Districts with cases in 2011 Districts with cases in current week
    • Vaccine Derived Polio Virus (VDPV) India, 2011 *Dots are randomly placed within blocks (Sub-districts) Data as of 05 Dec 2011 Districts with cases in 2011 Districts with cases in current week = Most recent P2 VDPV case = Most recent P3 VDPV case
    • Wild Polio Cases by Type (P1, P3) and Month of Onset India, 2007-2011 Data as of 05 Dec 2011
    •  
    • But why talk about IPV now?
      • “ The primary challenge to India’s energetic and comprehensive polio eradication efforts is the failure of the vaccine to optimally protect children in the remaining infected areas of the country.”
      • WHO (GPEI. Annual Report 2008)
      • Concerns about VAPP is being increasingly realized.
        • Reemergence of type 2 poliovirus in the form of VDPV
        • Reintroduction of wild PV circulation in previously polio-free countries through importations
      • GOI has recognized the need for IPV in our country and granted license for use in India (50 years after its development).
      • Role of IPV in ‘Polio End Game’ – WHO position
      • IAP recommendations
        • Suboptimal OPV efficacy
        • Inadequate Herd effect
        • Vaccine Associated Paralytic Poliomyelitis (VAPP)
        • Vaccine Derived Polio Virus (VDPV)
      Issues Surrounding the Use of OPV
    • Polio is Still Endemic in 4 Countries, Reflecting both “Failure to Vaccinate” and “Vaccine Failure” WHO. Polio Case count. Available at: http://www.who.int/immunization_monitoring/en/diseases/poliomyelitis/case_count.cfm , 2009 Graphs from WHO. Polioeradication. Progress & Prospect. 2008 Roberts. Science , 2009 W. Uttar Pradesh Bihar Rest of country High risk Medium risk Rest of country In Nigeria, high “failure to vaccinate” In India, polio cases despite high coverage, thus “high vaccine failure” 0 doses 1-3 doses 4-6 doses 7+ doses OPV doses administrated per area in Nigeria 2003-2008 OPV doses administrated per area in India 2003-2008 % of children < 5 years receiving doses % of children < 5 years receiving doses
    • Seroconversion after 3 doses of OPV
      • Industrialized versus low-income countries
        • 95% Seroconversion in industrialized countries
      • Seroconversion in low-income countries
      Review of 32 studies. Patriarca, Wright & John. Rev Infect Dis 1991; 13:926-39 Type Weighted average seroconversion 1 2 3 73% 90% 70%
    • Paralytic polio cases are occurring predominantly among the children who had received 4 or more doses of vaccine, and lately among those who had received more than 7 doses of OPV. On the other hand among the polio cases percentage of unvaccinated children is very low. In case children develop paralytic disease after taking many doses of OPV, it means that many doses of vaccine had failed to provide protection.
    • VAPP: A Rare But Serious and Inevitable Adverse Event Associated with OPV
      • Vaccine-Associated Paralytic Polio :
        • Definition: PP in vaccinee following OPV administration
        • Cause: Mutation of vaccine virus during replication in the gut of vaccinee (reversion to neurovirulence)
        • Form: VAPP undistinguishable from naturally occurring polio
          • Same incubation period, range of severity and Case Fatality Rate
        • May affect both vaccinees & close contacts
      Sutter et al. Vaccines , 2008 Paul. Vaccine , 2004 John. Bull of the WHO , 2004
    • VDPV: No Longer Just a Theoretical Concern
      • Vaccine Derived Polio Virus or VDPVs:
        • Definition: derivatives of Sabin OPV strains exhibiting 1-15% divergence in the sequence of viral protein vp1
        • Origin: accumulation of mutations by
          • Replication of the live vaccine strains within the vaccinee’s guts
          • Recombination with other enteroviruses
        • Potential to cause paralytic polio in humans and sustained circulation
        • Factor favoring emergence & spread are same as for wPV :
          • Low OPV coverage
          • Poor sanitation
          • High population density
          • Tropical conditions
        • 3 Types cVDPV, iVDPV, aVDPV
      WHO. WER , 2006
      • Particular concern: re-emergence of type 2 (as VDPV) whereas the wild type was declared eradicated in 2002 and reported in 5 independent cVDPV outbreaks since then
      • According to some experts: “more likely several million individuals were infected during these events, and many thousand more have been infected by VDPV lineages within outbreaks which have escape detection”
      2000- July 2009: At Least 13 cVDPV Outbreaks in 12 Countries Caused et Least of 300 Paralytic Polio cases DOR / HAITI 2000-01 VDPV 1 21 cases NIGER 2006 VDPV 2 2 cases NIGERIA 2005-08 VDPV 2 148 cases DR CONGO 2008 VDPV 2 11 cases MADAGASCAR VDPV 2 2001-02 5 cases 2005 3 cases MYANMAR 2006-07 VDPV 1 5 cases INDONESIA 2005 VDPV 1 46 cases CHINA 2004 VDPV 1 2 cases CAMBODIA 2005-06 VDPV 3 2 cases PHILIPPINES 2001 VDPV 1 3 cases ETHIOPIA 2008-09 VDPV 2 4 cases WHO. cVDPV 2000-2008. Available at: http://www.polioeradication.org/content/general/cvdpv_count.pdf , 2009 GPEI.Strategic Plan 2009-2013. Available at: http://www.polioeradication.org/content/publications/PolioStrategicPlan09-13_Framework.pdf ,2009 Wringe et al. Plos One , 2008 INDIA 2009 VDPV 1, 2 2 & 18 cases
    •  
    • The OPV Paradox – how OPV Use May Compromise the Final Goal of Eradication
        • Given risk of VAPP and VDPV associated with OPV, continued use of OPV may end up causing more cases of polio than wild polio virus ( OPV paradox )
      WHO. cVDPV 2000-2008. Available at: http://www.polioeradication.org/content/general/cvdpv_count.pdf , 2009 GPEI. Strategic Plan 2009-2013. Available at: http://www.polioeradication.org/content/publications/PolioStrategicPlan09-13_Framework.pdf ,2009 WHO. WER , 2004 Jacob. Bull of the WHO , 2002 Dowdle et al. Rev Med Virol , 2003 RISK FREQUENCY GLOBAL ESTIMATES VAPP 2-4 per million birth cohort 250-500 cases/year (WHO) 400-800 cases/year (other experts’ estimate) cVDPV 13 independent cVDPV outbreaks in 12 countries since 2000 iVDPV 33 cases since 1962
    • eIPV: The Vaccine of Choice for Today and the Future
        • High Immunogenicity Even After 2 Doses
        • Long-term Persistence of Antibodies
        • Good Efficacy / Effectiveness
        • Good Herd Immunity
        • Favorable Health Economics
    • eIPV: High Immunogenicity, Even After 2 Doses
        • High immunogenicity of IPV even in developing and tropical countries where OPV is suboptimal
        • High immunogenicity after 2 doses (including 27 developing countries) :
          • In 30 trials involving >4500 subjects, seroprotection against poliovirus:
            • 89-100% against type 1
            • 92-100% against type 2
            • 70-100% against type 3
        • Immunogenicity expectedly reinforced after 3rd dose
          • In 48 trials involving >6000 subjects
            • 95-100% seroprotection rates against all 3 types
        • Comparative study in India, 1990s
        • 92% efficacy of IPV vs 66% for OPV
        • (3 doses of respective vaccines)
      Polio Eradication Committee et al. Indian Pediatr , 2008 Plotkin & Vidor. Vaccines , 2008
    • IPV Provides Good Herd Immunity
      • Herd immunity:
        • Protection of the population to a greater extent than that expected by the actual population vaccination coverage
      • Excellent herd immunity reported wherever IPV used on large scale
        • e.g. : USA
      John. Expert Rev Vaccines , 2009 Stickle. Am J Public Health , 1954 Paralytic Poliomyelitis Cases Expected with or without Vaccine use, 1951-1954 Observed Expected in absence of vaccine use Expected with vaccine effect limited to vaccinees
    • Role of OPV + eIPV
      • Better mucosal immunity of OPV + IPV
      • Very low risk of VAPP – early OPV protection against VAPP by maternal antibodies. Subsequently protected by IPV. IPV alone may not be enough.
      • Higher seropositivity of OPV + IPV in multiple trials in Gambia, Oman, Thailand, Israel & Pakistan.
      • Benefit of continuing the government policy regarding OPV with highly predictable immunogenicity & efficacy of IPV.
      OPV & IPV are not contradictory but complementary !
    • Indian Academy of Pediatrics: Schedules
        • OPV at birth,
        • OPV and IPV at 6, 10 and 14 weeks.
        • OPV and IPV at 15-18 mths and
        • OPV at 5 years.
        • OPV on all NID’s and SNID’s.
      Indian Pediatrics 2008; 45: 635-648 Polio immunization naïve child Child has received OPV primary series
        • IPV given as two doses at 2 month interval
        • Continue OPV with DPT booster, and on all NID’s and SNID’s
        • IPV should be the preferred vaccine
        • The schedules are as before with a booster dose of IPV at 5 years
      Indian Academy of Pediatrics: Schedules Immunocompromised child Indian Pediatrics 2008; 45: 635-648
    • ‘ End game’ & ‘Post –eradication’ strategy – IAP PEC
      • End game - Use b-OPV for SIA’s, and add IPV for highly endemic region.
      • Post eradication – Introduce IPV and try to achieve high coverage before discontinuing OPV. Start with south states free of wild polio  gradually universal use. Continue OPV through 3 Pulse NIDs until WPV transmission stopped.
    •