Polio Eradication and End Game Strategy

IPV IntroductionBy M.N MunyoroNPO/EPI, WHO

1. Polio Endgame Objectives

2. Circulating Polio viruses

3. Components of Endgame Plan 2013-2018

4. Rationale for OPV withdrawal

5. WHO SAGE Recommendation for IPV introduction

6. Planning considerations

7. Resources

Key messages in this presentation

Background

• Poliovirus eradication is a programmatic emergency for global public health, World Health Assembly, 2012

• In response, the Polio Eradication and Endgame Strategic Plan 2013-2018 was developed and endorsed by WHA, 2013

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Circulating polioviruses

• 99% reduction in cases of wild poliovirus since 1988• Type 1 (328 cases to date in 2013†)• Type 2 (eliminated worldwide in 1999)• Type 3 (none detected since November 2012)

Wild

• Vaccine derived polioviruses (VDPV)• Most are circulating VDPVs (cVDPVs)*• ~46-184 per year since 2008• Type 2 cVDPVs account for 97% of cVDPVs

VDPVs*

• Vaccine-associated paralytic poliomyelitis (VAPP)**• Estimated ~250-500 globally per year• Type 2 accounts for about 40% of VAPP

VAPP**

† Per Polio This Week Numbers found at http://www.polioeradication.org/Dataandmonitoring/Poliothisweek.aspx*Other extremely rare VDPVs include primary immunodeficiency VDPVs (iVDPVs) and ambiguous VDPVs (aVDPVs)**Refers to spontaneous reversion to neurovirulence of one of the attenuated viruses in OPV. VAPP occurs in OPV recipients or their close contacts in contrast to cVDPVs which are widely transmitted in a community and are not likely to be related to contact with a recent vaccine recipient.

OPV

re

late

d

IPV introduction

• Polio detection & interruption

• RI Strengthening &OPV withdrawal

• Containment & Certification

• Legacy Planning

Components of Endgame Plan, 2013-18

2013 2014 2015 2016 2017 2018

Virus detection & interruption

Last wild polio case Certification

RI strengthening & OPV withdrawal

Containment & certification

Introduce IPV

Wild virus interruption

Outbreak response (esp. cVDPVs)

RI strengthening &OPV2 'readiness'

OPV 1 & 3'readiness'

Legacy Planning

Finalize long-term containment plans

Complete containment & certification globally

ConsultationMainstream polio

functions, infrastructure & learnings

Last OPV2 use

Major Objectives

1. WHY do we need to withdraw OPV ?

Some questions to help understand the rationale for OPV withdrawal

• OPV has the potential to mutate and cause disease and outbreaks – cVPDV

• With eradication of wild virus it would no longer be justified to use OPV

2. WHY withdraw OPV2 first (switch tOPV bOPV)?

• Currently, the risks of using OPV2 outweighs its benefits Wild PV2 has likely been eradicated – last case 1999 Type 2 OPV is leading cause of cVDPV outbreaks• bOPV is available and effective• Prepares for complete OPV withdrawal • Bonus – IPV introduction will help with eradication of wild

virus by enhancing immunity to type 1 & 3

3. WHY introduce IPV before switching to bOPV?

Some questions to help understand the rationale for OPV withdrawal - continued

• Provide immunity PV type 2 – window of risk of exposure to type 2 cVPDV

4. WHY is the timeline for OPV2 withdrawal & IPV introduction condensed?

• OPV withdrawal is part of the polio eradication initiative which is operating in urgent timeframe; OPV withdrawal is an integral part of eradication and needs to be coordinated to maximize protection and minimize risk of future cases and outbreaks.

5. WHY not switch all tOPV to IPV all one time ?

•OPV continues to be the best vaccine for eradicating wild virus (easy administration, inexpensive, mucosal immunity); similar to above -- phased and coordinated OPV cessation is critical for achieving wild virus eradication and preventing vaccine associated disease and outbreaks.

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Rationale for introducing at least one dose of IPV prior to the trivalentOPV-bivalentOPV switch

Reduce risks associated with OPV2 cessation

- Lower risk of re-emergence of type 2 polioviruses

Facilitate interruption of transmission with the use of monovalent OPV2 if type 2 outbreaks occur

Boost immunity against types 1 & 3 thus hastening polio eradication

IPV

IPV introduction

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Why withdraw OPV?

As wild polioviruses are eradicated, number of cases related to polio vaccine (VAPP plus

cVDPVs) exceeds number of cases related to wild poliovirus (as of 5 Nov. 2013)

A hypothetical scenario of estimated VAPP/cVDPV cases

?

IPV introduction

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Objective 2 of The Plan

Strengthen routine immunization

systems

• Into routine immunization schedule

• Prior to OPV withdrawal

Introduce at least one dose of IPV

Withdrawal OPV in phases

Phase 2: withdraw bOPV

Switch from trivalent OPV (tOPV) to bivalent OPV (bOPV)

Phase 1: remove type 2

component of OPV

IPV introduction

• All countries should introduce at least one dose of IPV into their immunization schedules by end of 2015.

• IPV is an additional dose to OPV and not a replacement. For example, in an OPV-only using country IPV should be administered in addition to the 3-4 doses of OPV in the primary series.

• This dose should be administered during the immunization contact at or after 14 weeks. For example, at the DPT3 or Penta3 visit.

DRAFT WHO SAGE Working Group recommendation on IPV schedule

IPV introduction – Other considerations

1. Is country planning to introduce another new vaccine before end of 2015?

2. Is IPV already licensed by NRAs?

3. Results of supply system and cold chain assessments

4. Financing /subsidizing mechanisms- for GAVI & Non GAVI countries

5. Availability of technical assistance

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Planned use of IPV: IPV Rationale Summary

IPV induces immunity in a proportion of children which will protect them against polio caused by

vaccine viruses (VAPP and cVDPVs) and polio caused by wild poliovirus

- IPV should lower risk of re-emergence of type 2 polioviruses

- IPV in conjunction with bOPV will decrease the number of cases of VAPP caused by types 1 and 3

- IPV will boost immunity to types 1 and 3 which should hasten eradication of types 1 and 3 wild polioviruses and reduce polio disease caused by types 1 and 3 cVDPVs

- IPV by inducing immunity to type 2 will facilitate outbreak control with mOPV2 should type 2 viruses be reintroduced

− A proportion of the population will already be immune resulting in a higher level of immunity after a dose of mOPV2 in

outbreak control than after a dose of mOPV2 to contain an outbreak in a completely susceptible population

The higher the IPV coverage the better, but even low coverage will provide direct benefit to those

vaccinated and greatly facilitate building population immunity in an emergency response

IPV introduction

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Features of Inactivated Polio Vaccine (IPV)

Not a live vaccine – no risk of VAPP or VDPVs Must be administered by injection Trivalent – produces antibodies to types 1, 2 and 3 poliovirus A high proportion of vaccinees, generally > 95% of children, have serum neutralizing

antibodies after 3 doses to all three polio serotypes Appears equivalent to OPV in inducing pharyngeal immunity Inferior to OPV in inducing gut immunity More costly to produce than OPV

− Price now generally in excess of $2.00 per dose but with increased demand, price likely to decrease

− Collaborations & investigations underway to explore two “low cost” IPV options:◊ fractional dose intradermal ◊ adjuvanted intramuscular IPV

− GAVI will cover the full cost of purchase for GAVI eligible countries

IPV introduction

http://www.who.int/immunization_delivery/adc/inactivated_polio_vaccine/en/

Resources on live website

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