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Module 1 Introduction to the polio endgame rationale and IPV vaccine

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1 Module 1 Introduction to the polio endgame rationale and IPV vaccine
Training for Inactivated Poliovirus Vaccine (IPV) introduction Module 1 Introduction to the polio endgame rationale and IPV vaccine

2 Learning objectives At the end of the module, the participant will be able to: Understand poliovirus transmission, poliomyelitis disease and global progress toward polio eradication Recognize the vaccines available against polio and the risks and benefits of each Describe the rationale for introducing IPV into the routine immunization schedule Duration 25 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? 3 What is the status of polio eradication globally? 4 Why do we need IPV? 5

4 What is polio disease? Polio (also called Poliomyelitis) is a highly infectious disease caused by a virus The virus invades the nervous system and can cause permanent paralysis Polio is spread through person-to-person contact and can spread rapidly through a community Most infected people (72%) have no symptoms However, 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 contagious Poliovirus is spread mostly by the fecal-oral route Primary mode of transmission – passage of the virus in stool to the mouth of another child Can also be spread through saliva or droplets from a sneeze or cough To 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 transmission Transmission 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 bathroom Virus transferred to objects from hands Virus transferred to another child’s hands Virus transferred ingested Next cycle of infection

6 Advances in Polio Eradication
416 cases reported in 2013 359 cases reported in 2014 3 endemic countries : 7 countries with re-established transmission 1988 350,000 cases 125 endemic countries World Health Assembly resolved to eradicate polio To 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 2013 Two 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 worldwide Second, 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 1999 Type 3 – last case reported in Nov (more time is needed to certify eradication) To the facilitator: Explain to the participants the types of polioviruses Polioviruses 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 3 most commonly used OPV in routine immunization globally Bivalent OPV (bOPV): types 1 and 3 commonly used in supplementary immunization activities (SIAs) Monovalent OPV (mOPV): type 1, 2 or 3 primarily used for SIAs in areas where only type 1 or type 3 is circulating OPV 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 paralysis Vaccine Associated Paralytic Polio (VAPP) Vaccine virus spontaneously changes and becomes capable of causing disease Globally 1 case per 2.4 million doses administered; ( cases/year) 40% of VAPP are from type 2 OPV Region of the Americas: One case of VAPP per 7.68 million doses administered 24% 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 coverage Low coverage is the main factor for the occurrence of cVDPVs 97% 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. 359 To the facilitator: WPV and vaccine-related polio cases Although 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 during Post-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 emergency Under this plan to achieve a polio-free world, they recommend that the use of OPV must eventually be stopped worldwide OPV will be withdrawn in 2 phases beginning with type 2 OPV Type 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 eradication Because 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 bOPV Phase 2: withdrawal of bOPV after the certification of eradication of wild polioviruses The 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 withdrawn Rationale for this includes: Contribute to the final phase of polio eradication To reduce risks associated with type 2 OPV withdrawal Maintain 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) virus Administered by drops Highly successful in reducing transmission in developing countries as part of eradication strategy Inexpensive Easy to administer Provides humoral immunity and mucosal/gut immunity Protects close contacts who are unvaccinated Killed virus Administered by injection Highly effective and safe Used commonly in developed countries More expensive than OPV Requires trained health workers Provides humoral immunity Carries no risk of VAPP or cVDPV Both 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 achieved When use of OPV is eventually stopped, IPV will continue to provide full protection Introducing IPV to our community is another opportunity to remind caretakers about the importance of vaccinations IPV does not cause any paralysis and is a very safe vaccine To 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 Messages Polio is a highly contagious viral disease that can spread rapidly through person- to-person contact causing permanent paralysis There are 3 types of wild poliovirus but only type 1 remains in circulation today OPV is inexpensive and effective at reducing polio transmission in developing countries, but carries a risk of VAPP and VDPV All use of OPV must stop for the world to be completely polio-free IPV 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 IPV Next modules of this training will explain how to: Store the vaccine Determine vaccine eligibility Administer the vaccine Record the vaccine dose Monitor Events Supposedly Attributable to Vaccination or Immunization Communicate with caregivers about the vaccine 16

17 End of module Thank you for your attention!

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