Presentation on theme: "Module 1 Introduction to the polio endgame rationale and IPV vaccine"— Presentation transcript:
1 Module 1 Introduction to the polio endgame rationale and IPV vaccine Training for Inactivated Poliovirus Vaccine (IPV) introductionModule 1Introduction to the polio endgame rationale and IPV vaccine
2 Learning objectivesAt the end of the module, the participant will be able to:Understand poliovirus transmission, poliomyelitis disease and global progress toward polio eradicationRecognize the vaccines available against polio and the risks and benefits of eachDescribe the rationale for introducing IPV into the routine immunization scheduleDuration25 minutes
3 Key issues 1 2 3 4 5 What is polio disease? How is polio spread? What types of viruses exist and what vaccines do we have against them?3What is the status of polio eradication globally?4Why do we need IPV?5
4 What is polio disease?Polio (also called Poliomyelitis) is a highly infectious disease caused by a virusThe virus invades the nervous system and can cause permanent paralysisPolio is spread through person-to-person contact and can spread rapidly through a communityMost infected people (72%) have no symptomsHowever, one in 200 infections leads to permanent paralysis (can’t move parts of the body) and even death
5 How does poliovirus spread? Poliovirus infection is highly contagiousPoliovirus is spread mostly by the fecal-oral routePrimary mode of transmission – passage of the virus in stool to the mouth of another childCan also be spread through saliva or droplets from a sneeze or coughTo the facilitator:Explain to the participants how polio is spread.Polio is spread through person-to-person contact typically through fecal-oral route but can also spread through droplets from saliva, sneeze or a cough.When a child is infected with wild poliovirus, the virus enters the body through the mouth and multiplies in the nasopharynx and intestine.It is then shed into the environment through oropharyngeal secretions for about a week and through feces for 3 to 6 weeks.Poliovirus is highly infectious and nearly all susceptible household contacts of infected persons can acquire infection. Poor sanitation and water quality are risk factors to the disease transmissionTransmission is especially high in situations of crowding and poor hygiene and sanitation.Child excretes virus in stool and does not wash hands after using the bathroomVirus transferred to objects from handsVirus transferred to another child’s handsVirus transferred ingestedNext cycle of infection
6 Advances in Polio Eradication 416 cases reported in 2013359 cases reported in 20143 endemic countries: 7 countries with re-established transmission1988350,000 cases125 endemic countriesWorld Health Assembly resolved to eradicate polioTo the facilitator:Describe to the progress of polio from 1988 to 2013 and the remaining challenges.The eradication of polio is a top global health priority.Since the World Health Assembly (WHA) announced a goal to eradicate polio in 1988, thereby creating the Global Polio Eradication Initiative (GPEI), the number of polio cases has drastically declined from ~350,000 cases per year in 1988 to only 416 cases in 2013Two important aspects of the current global situation of polio warrant ongoing use of OPV until polio transmission is interrupted.First, WPV is still endemic in three countries (Pakistan, Afghanistan, and Nigeria) that continue to be reservoirs for re-infecting other countries worldwideSecond, in 2013 and 2014, polio cases were also detected in seven additional countries (Somalia, Kenya, Ethiopia, Cameroon, Syria, Iraq, and Equatorial Guinea) that were previously polio free.Until polio transmission is interrupted in all of these high transmission settings, OPV will be a critical component of the Eradication Plan.6
7 Types of polioviruses Wild poliovirus (WPV) – 3 serotypes Type 1 – 359 cases in 2014 this is the only type of WPV in circulation today)Type 2 – eliminated in 1999Type 3 – last case reported in Nov (more time is needed to certify eradication)To the facilitator:Explain to the participants the types of poliovirusesPolioviruses can be wild or vaccine-related.Wild polioviruses (WPVs) are those that circulate naturally and are classified into three distinct serotypes (type 1, type 2, and type 3).Since November 2012, all cases of polio related to wild virus have been Type 1. There has been no natural circulation of Type 2 WPV since 1999 when the last case was last detected in Aligarh, India. Type 3 WPV was last detected in November 2012, although absence of virus detection for one year is not sufficient for certifying eradication.
8 Types of Oral Polio Vaccines Trivalent OPV (tOPV): types 1, 2 and 3most commonly used OPV in routine immunization globallyBivalent OPV (bOPV): types 1 and 3commonly used in supplementary immunization activities (SIAs)Monovalent OPV (mOPV): type 1, 2 or 3primarily used for SIAs in areas where only type 1 or type 3 is circulatingOPV is still the primary vaccine for eradication
9 Paralysis associated with OPV OPV offers effective protection against polio, but... in very rare cases it can lead to paralysisVaccine Associated Paralytic Polio (VAPP)Vaccine virus spontaneously changes and becomes capable of causing diseaseGlobally1 case per 2.4 million doses administered; ( cases/year)40% of VAPP are from type 2 OPVRegion of the Americas:One case of VAPP per 7.68 million doses administered24% of VAPP cases are caused by the type 2 virus (28%- by type 1, and 31%-type 3)Circulating Vaccine Derived Poliovirus (cVDPV)Rare outbreaks caused by person-to-person spread of vaccine strain, which mutates/changes to a highly transmissible form capable of causing disease to the nervous system, in areas/countries with low coverageLow coverage is the main factor for the occurrence of cVDPVs97% of cVDPVs are from type 2 OPV in recent years
10 WPV and vaccine-related polio cases 2009-2014* Through the use of OPV, polio cases related to the wild poliovirus have decreased.Today the number of polio cases due to OPV is greater than those related to the wild virus.359To the facilitator:WPV and vaccine-related polio casesAlthough OPV is the appropriate vaccine until polio transmission is interrupted, with ongoing use of OPV and control of polio disease related to wild virus globally, the estimated number of polio cases related to OPV has exceeded those related to wild virus. Low coverage is considered as one of the main factors for the occurrence of cVDPVs.This graph shows reported paralytic cases of wild polio virus and estimated cases of paralysis associated with OPV (VAPP and cVDPV) assuming ongoing use of OPV. Blue bars depict WPV cases reported to GPEI as of 21 May Red line depicts cases of VAPP and cVDPVs estimated to occur based on midpoint of estimated cases of VAPP globally (250 to 500) and the average number of cVDPVs reported annually duringPost-interruption of WPV transmission
11 Polio eradication plan In May 2012 the World Health Assembly of WHO declared poliovirus eradication to be a global public health emergencyUnder this plan to achieve a polio-free world, they recommend that the use of OPV must eventually be stopped worldwideOPV will be withdrawn in 2 phases beginning with type 2 OPVType 2 OPV has the two risks: VAPP and cVDPV – and is no longer needed for eradication – hence the type 2 containing OPV will be eventually withdrawn from use globally.To the facilitator:Explain to the participants the Polio eradicationBecause of this very low but real risk of polio associated with OPV, if the world is to remain free of polioviruses following eradication, then use of OPV ultimately will need to be stopped. To curtail the risk of polio associated with OPV (cVDPV and VAPP), the Endgame calls for a withdrawal of vaccine in two phases:Phase 1: removal of type 2 component of OPV, through a global switch from tOPV to bOPVPhase 2: withdrawal of bOPV after the certification of eradication of wild poliovirusesThe phased withdrawal of OPV related to the epidemiology of WPV and vaccine-related cases of polio occurring globally in the past decade.
12 Polio eradication plan (continued) WHO’s Strategic Advisory Group of Experts (SAGE) recommends that all countries introduce at least one dose of IPV into their routine immunization schedule by the end of 2015, before type 2 OPV is withdrawnRationale for this includes:Contribute to the final phase of polio eradicationTo reduce risks associated with type 2 OPV withdrawalMaintain immunity against polio type 2 during the global withdrawal
13 Comparison of OPV and IPV? Oral polio vaccine (OPV)Inactivated polio vaccine (IPV)Live, attenuated (weakened) virusAdministered by dropsHighly successful in reducing transmission in developing countries as part of eradication strategyInexpensiveEasy to administerProvides humoral immunity and mucosal/gut immunityProtects close contacts who are unvaccinatedKilled virusAdministered by injectionHighly effective and safeUsed commonly in developed countriesMore expensive than OPVRequires trained health workersProvides humoral immunityCarries no risk of VAPP or cVDPVBoth vaccines are needed to fully eradicate polio!
14 Why IPV?IPV introduction sets the stage for ending OPV use entirely after WPV eradication has been achievedWhen use of OPV is eventually stopped, IPV will continue to provide full protectionIntroducing IPV to our community is another opportunity to remind caretakers about the importance of vaccinationsIPV does not cause any paralysis and is a very safe vaccineTo the facilitator:Describe to the participants the rationale for IPV.The primary role of introducing one dose of IPV into routine immunization programs is to reduce risks associated with OPV withdrawal and possible reintroduction of polioviruses.The initial phase of OPV withdrawal – switch from trivalent OPV to bivalent OPV-- would lead to a gradual increase in the number of persons susceptible to type 2 poliovirus resulting in three main risks to the population.1) Immediate time-limited risk of cVDPV2 emergence;2) Medium and long-term risks of type 2 poliovirus re-introduction from a vaccine manufacturing site, research facility, diagnostic laboratory, or a bioterrorism event.3) Spread of virus from rare immune deficient individuals who are chronically infected with OPV2.A reintroduction of poliovirus or cVDPV2 emergence could potentially result in a substantial polio outbreak or even re-establishment of global transmission.IPV will reduce these risks after OPV withdrawal and provide protection against polio without causing side effects.
15 Key MessagesPolio is a highly contagious viral disease that can spread rapidly through person- to-person contact causing permanent paralysisThere are 3 types of wild poliovirus but only type 1 remains in circulation todayOPV is inexpensive and effective at reducing polio transmission in developing countries, but carries a risk of VAPP and VDPVAll use of OPV must stop for the world to be completely polio-freeIPV is being introduced to provide protection against all 3 serotypes, while OPV is being phased out, to help us make the world polio free
16 Inactivated Polio Vaccine (IPV) Our country is about to introduce IPVNext modules of this training will explain how to:Store the vaccineDetermine vaccine eligibilityAdminister the vaccineRecord the vaccine doseMonitor Events Supposedly Attributable to Vaccination or ImmunizationCommunicate with caregivers about the vaccine16