Vaccine 27 (2009) 3700–3703

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Short communication

Why polio has not been eradicated in India despite many remedial interventions?

Yash Paul ∗

Maharaja Agrasen Hospital, Vidhyadhar Nagar, Jaipur 302023, India

a r t i c l e i n f o

Article history:Received 22 March 2009Accepted 24 March 2009

a b s t r a c t

Oral polio vaccine has reduced the incidence of polio in India and many states have been polio free for along time while occasional polio cases are occurring in some states. On the other hand more than 96% of

Available online 16 April 2009

Keywords:Polio eradicationPP

polio cases being reported in India are occurring in Uttar Pradesh and Bihar. The current polio scenarioindicates that oral polio vaccines cannot eradicate polio from Uttar Pradesh and Bihar because somechildren from these two states show poor response to OPV. There is an urgent need for re-appraisal ofpolio eradication strategy.

© 2009 Elsevier Ltd. All rights reserved.

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. Introduction

Pulse polio immunization was started in India in 1995. 2 Octobernd 14 November were assigned as pulse polio days, polio eradica-ion was expected to occur by end 2000. But polio eradication hasot occurred so far, despite many remedial interventions.

Following remedial steps have been taken:

1. In 1999 quantity of P3 vaccine viruses was increased from500,000 to 600,000 per dose of two drops of OPV.

. In 1999 number of vaccination rounds were increased to 5–6rounds per year for some states.

. In 2005 monovalent OPV1 (mOPV1) and monovalent OPV3(mOPV3) were introduced in Uttar Pradesh.

. In 2007 mOPV1 and mOPV3 were introduced in Bihar.

. In 2007 number of vaccination rounds for Uttar Pradesh wereincreased to a round every month.

It can be said that all the above mentioned interventions wereifferent steps taken in the right direction. Potency of trivalent vac-ine had been increased, monovalent vaccines which are supposedo be 2–3 times more effective had been introduced in the regionsith high incidence of polio cases and rounds of immunization

ere also increased, but polio has not been eradicated. On the otherand, lately the polio incidence has increased as can be seen inable 1.

∗ Address: A-D- 7, Devi marg, Bani Park, Jaipur 302016, India. Tel.: +91 141 2314774.E-mail address: dryashpaul2003@yahoo.com.

264-410X/$ – see front matter © 2009 Elsevier Ltd. All rights reserved.oi:10.1016/j.vaccine.2009.03.078

2. Factors which have adverse effect on polio eradication

2.1. Environmental factors

Poor sanitation helps in transmission of causative organismswhere spread of infection occurs by faeco-oral route, and over-crowding results in increased chances of spread of air-borneinfections. Poliovirus spreads by both methods, thus poor sanita-tion and overcrowding help spread of disease, and have adverseeffect on polio eradication.

2.2. High birth rate

High birth rate in the community results in increased populationof vulnerable individuals who may lead to high transmission of thedisease.

2.3. Infrastructure facilities

Shortage of health workers and facilities may result in poor vac-cine coverage.

2.4. Social factors

Some religious groups or ethnic groups show reluctance or resis-tance to vaccination because of some beliefs or misinformationwhich may result in low vaccine coverage.

2.5. Vaccine failure

In case adequate antibodies to provide protection are not gen-erated after appropriate number of doses of a vaccine, it is called acase of vaccine failure. Factors for poor antibody generation by OPVmay be in the vaccine and/or in the host.

Y. Paul / Vaccine 27 (2009) 3700–3703 3701

Table 1Number of polio cases in different states from 1998 to 2008 as on 14 March 2009.

S. no. States 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

1 Andaman & Nicobar 0 0 0 0 0 0 0 0 0 0 02 Arunachal Pradesh 0 0 0 0 0 0 0 0 0 0 03 Dadra & Nagar Haveli 1 0 0 0 0 0 0 0 0 0 04 Daman & Diu 5 0 0 0 0 0 0 0 0 0 05 Goa 2 0 0 0 0 0 0 0 0 0 06 Kerala 0 1 0 0 0 0 0 0 0 0 07 Lakshadweep 0 0 0 0 0 0 0 0 0 0 08 Manipur 0 0 0 0 0 0 0 0 0 0 09 Meghalaya 0 0 0 0 0 0 0 0 0 0 0

10 Mizoram 0 0 0 0 0 0 0 0 0 0 011 nagaland 0 0 0 0 0 0 0 0 0 0 012 Pondicherry 2 0 0 0 0 0 0 0 0 0 013 Sikkim 0 0 0 0 0 0 0 0 0 0 014 Tripura 0 0 0 0 0 0 0 0 0 0 015 Assam 1 0 0 1 0 1 0 0 2 0 116 Himachal Pradesh 0 0 0 0 0 0 0 0 1 0 017 Jammu & Kashmir 0 0 0 0 1 0 0 0 1 0 018 Tamil Nadu 91 7 0 0 0 2 1 0 0 0 019 Andhra Pradesh 96 21 0 0 0 21 1 0 0 5 120 Chandigarh 1 2 1 0 1 0 0 0 1 0 021 Chhattisgarh 15 3 0 0 1 0 0 0 0 0 022 Delhi 47 73 3 3 24 3 2 1 7 2 523 Gujarat 164 9 2 1 24 3 0 1 4 1 024 Haryana 39 19 4 5 37 3 2 1 19 6 225 Jharkhand 27 8 1 2 12 1 0 2 1 0 026 Karnataka 71 21 8 0 0 36 1 0 0 1 227 Madhya Pradesh 107 17 2 0 21 11 0 0 3 0 128 Maharashtra 121 18 7 4 6 3 3 0 5 2 229 Orrisa 49 0 0 0 4 2 0 0 0 1 230 Punjab 9 4 0 5 2 1 0 1 8 1 231 Rajasthan 63 18 0 0 41 4 0 0 1 3 232 Uttarakhand 36 16 1 3 14 0 1 1 13 6 233 West Bengal 26 21 8 1 49 28 2 0 1 2 234 Bihar 131 115 49 27 121 18 41 30 61 503 23335 Uttar Pradesh 845 757 178 216 1242 88 82 29 548 341 305

Total cases in India 1934 1126 265 268 1600 225 136 66 676 874 559Bihar and UP %age 50.46 77.44 85.66 90.67 85.18 47.11 90.44 89.39 90.08 96.33 96.42

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.5.1. In the vaccineThe potency of OPV can be affected during manufacture (less

ikely), transportation or storage (probably), because very efficientold-chain system is required as OPV happens to be a very heatabile vaccine. During the hot summer seasons, electric power isupplied in most parts of India for few hours a day, which candversely affect the potency of OPV.

.5.2. In the hostMultiple factors in the vaccinee may be responsible for poor

esponse to the vaccine. In the vaccine recipients presence of othernteroviruses, malnutrition, immunosuppression due to diseaser drugs can be reasons for a poor response to OPV. It is a well-nown fact that in India and many other countries doctors, quacksnd practitioners of other systems of medicine administer corticos-eroids even for trivial ailments [1].

Response to OPV has been very variable. It was known sinceong that children in tropical and developing countries respondoorly to OPV [2–5]. Poor seroconversion had been reported from

ndia during 1970s [6–8]. But, precise reasons for poor response

ere not known. The problem of non-responders to hepati-

is B vaccine is known since 1980s and measles vaccine since990s [9]. In 2004 Newport et al. had reported role of geneticactors in antibody response to OPV [10]. Thus, some geneticactors in the vaccinees may be responsible for poor responseo OPV.

2.6. Resistant polioviruses

Vaccine failure sometimes leads to vaccine ‘pressure’ wherebythe organism that the vaccine was designed to protect againstmutates and evades detection by the vaccine-induced immuneresponse [9].

3. What needs to be done?

All the factors that have an adverse effect on polio eradicationexist in India; in varying degrees in different parts of the coun-try, i.e. there is a need to take remedial steps in many direction,which include improving the sanitation, reducing overcrowdingand improving the nutrition and the general health of the popu-lation, especially those of the children. But, special attention needsto be paid to the following factors which have major impact on polioeradication programme.

3.1. Vaccine

The nation has been repeatedly assured that the vaccine beingadministered is of high potency. Experts had stated: “Hence, it is

very reassuring to note that the Oral Polio Vaccine (OPV) used inthe country is adequately potent” [11]. But, as is being observed thatamong the polio cases proportion of the children who had receivedmany doses of OPV is on the rise as can be seen in Table 2, suggest-ing that vaccine failure is on the rise, thus this warrants evaluation

3702 Y. Paul / Vaccine 27 (2009) 3700–3703

Table 2Number of OPV doses received by polio cases, 1998–2007.

OPV doses 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

0 dose 15% 14% 14% 9% 16% 14% 4% 0% 3% 1%1–3 doses 47% 45% 28% 31% 41% 35% 11% 11% 10% 3%4–7 doses 32% 34% 35% 41% 33% 34% 41% 44% 22% 12%> 11%

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f vaccine potency of the vaccine samples collected from differentlaces to rule out the probability of low potency vaccines beingdministered to some children.

.2. Vaccine coverage

“Some argue that the polio vaccines being administered in Indiare effective, but the data regarding the number of doses of theaccine for polio cases are false. According to them some parentso not take the children for vaccination to the booths during theulse polio immunization, and hide the children during house-to-ouse campaign, or tell the vaccinators that the child in questionad already been administered the vaccine. In case a child developsaralysis then the parents claim that the child had received manyoses of vaccine before developing the disease” [1]. This could berue, as no documents are provided to the parents for a child whereecord of polio vaccine doses can be made. Parents have to dependn their memory to recall the number of vaccine doses received bychild. Thus, some sort of documents should be provided to thearents for keeping the record of vaccine doses administered to ahild.

It is also true that some parents resist the administration of OPV,hich could be due to some misconceptions, especially among theuslims that OPV may cause infertility. Lately the vaccine coverage

as increased tremendously due to the efforts by the religious andocial leaders and advocacy by different celebrities. More efforts areequired to increase awareness and social mobilisation.

.3. Infrastructure

Lack of infrastructure, shortage of health workers and non-vailability of vaccine at a particular point of time may also beesponsible for poor vaccine coverage. It may also be true that toave their skin some false and higher vaccine coverage data mighte recorded by the health workers. These issues also need atten-ion.

.4. Hosts

Malnutrition, intercurrent infections and immunosuppressionue to disease or drugs may also be responsible for poor responseo OPV. Role of these factors cannot be denied, but, the fact that polioases are occurring predominantly in children from Uttar Pradeshnd Bihar cannot be overlooked.

A study by Grassly et al. had shown that children from Uttarradesh show poor response to OPV1 and OPV3, while children fromihar show slightly poor response to OPV1, but superior responseo OPV3 [12]. This different response to different strains of vaccineannot be due environmental factors or malnutrition alone. Thus,ome host factors in the children from different ethnic populations

eed to be looked into. The reasons for this different response coulde some genetic factors or some hitherto unidentified host fac-ors. This author had postulated that some genetic factors could beesponsible for poor response shown by some children from Uttarradesh and Bihar [13].

17% 44% 45% 65% 85%

3.5. Polio viruses

Since introduction of pulse polio immunization in 1995, appre-ciable and gradual decline in polio incidence had occurred, exceptfor high incidence of polio cases in 2002. In 2005 there were only 66polio cases and it appeared that polio eradication is about to occur.But depsite introduction of monovalent polio vaccines and furtherincrease in vaccination rounds, polio incidence increased sharply;there were 676 cases in 2006, 874 in 2007 and as on 14 March 2009559 cases had been reported for 2008. This would suggest that per-haps the polio viruses have undergone some mutations because ofhigh incidence of vaccine failure. There is the possibility that pri-mary vaccine failure may result in ‘vaccine pressure’, leading to thedevelopment of mutant polioviruses strains that are ‘resistant’ tothe antibody produced by the vaccine [9].

4. What do we do now?

It is high time that the policy makers redefine the goal: poliocontainment or polio eradication. For polio containment, admin-istration of tOPV with or without mOPV1 and mOPV3 can becontinued. In this situation, parents should be given autonomy todecide whether they opt for IPV for their children, with or with-out OPV. OPV should not be made compulsory and parents not becoerced to administer OPV to their children. Thus, OPV should bemade optional for those children who receive IPV.

If the goal is polio eradication, then it would be prudent for thepolicy makers to accept and acknowledge the limitations of OPV.IPV should be used as the exclusive tool for polio eradication in UttarPradesh and Bihar, because, it would be difficult to distinguish thechildren who may respond to OPV and those who may not showadequate response to OPV.

The policy makers will have to redefine the strategy for rest ofIndia. Polio cases are not occurring in many states for a long time fol-lowing OPV administration only. Because of constraints of resourcesOPV may be continued in these states but, sooner or later OPV willhave to be discontinued all over India to stop VAPP cases and avoidany risk to the community by VDPVs.

Acknowledgements

Competing interests: None.Funding: None.

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