T JACOB JOHN

T

Poliovirus infection is silent, inconsequential and undetected in the vast majority, which facilitates transmission from person to person. One in 160 to 1,000 children with first infection with each type of virus develops paralysis that we call polio [John 1993]. Birth rate and closeness of contact among children determine the speed of virus transmission, which in turn determines the age at which children develop polio (ibid). In the pre-vaccine era, in the US, 50 per cent were infected and immune by 15 years while in India the median age was (and is) 15 months, a huge difference with huge implications for prevention by vaccination (ibid).

The silent infection amplifies viruses to enormous numbers both in the nasopharynx and in the intestines and shed via the oral/nasal secretions and faeces. While some experts teach that infection transmits from faeces to mouth (faecaloral), all scientific observations point to the nasal route of transmission (through aerosol). Water-borne outbreaks, typical of faecal-oral infections, do not occur with polio [John 1993]. The age pattern of polio closely resembles respiratory-transmitted measles, quite unlike that of hepatitis A, a known faecal-oral transmitter. Finland faced polio outbreaks even after it had virtually got rid of hepatitis A transmission (ibid). This controversy about the route of transmission has a critical bearing on the choice of vaccine. If faecal-oral, the live oral polio vaccine (OPV, Sabin) is better; but if it is nasal, then the injected polio vaccine (IPV, Salk) is superior (ibid). OPV induces moderately better intestinal immunity but IPV induces vastly better naso-pharyngeal immunity (ibid). Finland eliminated polio in the 1960s by the exclusive use of IPV (ibid). The US reduced polio incidence by 99 per cent with IPV before OPV replaced it (ibid). The infection declined faster than the vaccination coverage, clearly showing a “herd effect”, a sign of mucosal immunity and prevention of re-infection (see below) (ibid). Later, the US switched back to IPV in order to eradicate vaccine viruses causing “vaccine associated paralytic polio” (VAPP).

Disadvantage of OPV

Environmental factors reflected in intestinal eco-milieu strongly interfere with intestinal infection by vaccine viruses fed orally, but they do not inhibit wild poliovirus infection, as transmission is by the nose. Such inhibition and consequent low effectiveness are a major disadvantage of OPV in tropical/developing country settings [John 1993]. Natural infection succeeds with tiny doses of wild viruses, whereas two million vaccine viruses in OPV, fed orally, infect only a minority of children (ibid). Both wild and vaccine viruses are one species with small genetic changes that alter neuro-virulence. Both share identical host cell receptors. No other biological factor, except the route of inoculation, can explain the paradox of one being excessively infectious and the other easily inhibited by intestinal factors.

Among the three wild poliovirus types, type 1 is the most infectious and virulent, but in OPV that is the least infectious and immunising [John 1993]. In Uttar Pradesh (UP) and Bihar we need high vaccine efficacy against type 1, but OPV fails miserably. OPV has disappointed everyone – it is both unsafe (everywhere) and inefficient (in developing countries with poor sanitation). On the other hand IPV is completely safe, bypasses the intestinal interference, immunises with far fewer doses than OPV, affords naso-pharyngeal immunity and importantly, is most effective against type 1 (ibid). The proprietary ownership of the original Sabin strains of OPV viruses rests with the World Health Organisation (WHO) and is like a “mascot” for the owner. That translated to “dogma” of its superiority with idealised properties – most of which are scientifically discredited. Yet, the dogma is believed by many. The faecal-oral transmission theory of natural infection was propagated mainly as a ruse to justify OPV. If all countries are divided into autonomous decision-makers and WHO-dependant decision-makers the contrast will be obvious – most of the former use IPV, the latter use OPV.

Once immunity develops, the child is protected from disease but not necessarily from re-infection. Natural immunity and that induced with IPV offer a more effective barrier to re-infection than OPV-induced immunity [John 1993]. Many outbreaks have been recorded in countries with high OPV coverage, all showing the full participation of vaccinated children as efficient links in the chains of transmission, although they are immune to disease (ibid). When type 1 poliovirus is re-introduced in a country that had eliminated it earlier, a huge outbreak may ensue – and has to be doused with nationwide campaigns with several doses of OPV as if the childpopulation had no mucosal immunity. This happened in Yemen and Indonesia in 2005.

Economic and Political Weekly December 23, 2006 In 2006, type 1 wild virus entered Bangladesh from India and spread nationwide in a very short time. On account of their sustained excellent routine immunisation programme, only 15 children developed polio in 10 districts. However, to interrupt transmission, four nationwide OPV campaigns had to be conducted, each achieving 100 per cent coverage (http://www.searo.who.int/EN/Section1226/ Section1635.htm). In IPV-using countries such reintroduction does not spread to vaccinated children on account of longlasting naso-pharyngeal immunity.

Protection against disease (due to antibodies in blood) and against re-infection (mucosal immunity) is a clearly dichotomous attribute of OPV-induced immunity [John 1993]. The current outbreak of type 1 polio in UP and Bihar in spite of average 15 doses per under-five child exemplifies the recurrent global problem of outbreaks in communities well vaccinated with OPV (ibid). Obviously the benefit, if any, of OPV-induced mucosal immunity does not last long. UP and Bihar had three consecutive outbreaks exactly at four-year periodicity (see table below). In three years sufficient “infection-susceptible” child-population accumulates to start and sustain another outbreak. The next outbreak will be in 2010 unless virus transmission is stopped in the interim by “fast-track and fail-safe” tactics. The window is only three years. The total numbers in successive outbreaks have dwindled, proportional to the increase in the vaccination efforts – number of campaigns and increasing coverage in each campaign. Such tempo may not be sustainable for long. The government of India (GoI) has not set a new target year for eradication, indicating both diffidence and pessimism, quite understandably born out of realism.

Notes: * Until October; outbreak years and numbers highlighted.

Birth rate determines the rate of entry of children into the pool of fully susceptible persons and the age pattern of disease indicates the rate of exit from that pool on account of infection and consequent immunity [John 1993]. Where there is a high density of population as well as a high birth rate, the entry of children into the susceptible pool is very fast and the frequency of infection in the very young, very high (ibid). These factors are responsible for the wide geographic variations in the “speed of circulation” of polioviruses and age-pattern of polio. Higher the speed, lower the age at first infection and of polio. Up until the 1990s India had one of the world’s highest speeds of transmission, highest incidence and youngest age distribution of polio. UP and Bihar have the worst end of the spectrum [Indian Journal of Medical Research 2004]. The speed with which infants are vaccinated, the number of doses, the per-dose efficacy and vaccine coverage will determine if the virus can be interrupted from transmission using OPV. The WHO policy of one cut-fits-all is untenable in UP and Bihar (ibid). The optimum number of doses required for protection from disease in near-100 per cent children in south India is 10 of OPV or three of IPV [John 1993]. Where the force of transmission is extremely high as in UP and Bihar, several more of OPV or onemore of IPV are needed during the next three to four years of life, particularly if transmission should be interrupted. The polio drama is virtually over by school entry age.

The critical period of most efficient but silent virus amplification – the driving engine of virus persistence and periodic seeding of outbreaks – is the first six months of life. For individual protection and for interruption of transmission, that age cohort must be covered by adequate immunisation, or else the battle will be lost. A routine immunisation programme reaches young infants – campaigns often miss them [John 1993]. When too many campaigns are conducted, walking children (above 1 year) are preferentially represented in booths, but small babies are kept home. When health workers seek them out by home visits the result is mixed – some families allow vaccination but many others suspect another motive behind this extraordinary interest in infants and refuse vaccination or hide the babies. In the total absence of a denominator census, the coverage measurement is at best “guesstimates”. High coverage and high number of doses per child are both skewed towards older children – an obvious lesson (and fatal error in eradication) from epidemiology of the age pattern of polio cases and the ground realities of routine and campaign vaccinations. “Pulse immunisation” had a different design and did not preferentially miss small babies – it is health system and community friendly (ibid).

Why Should India Eradicate Polio?

During the 1980s the annual incidence of polio was about 2 to 2.5 per 1,000 underfive children [John 1984]. That amounted to 1 per cent of children becoming paralysed, and an overall annual disease burden of 2,00,000 to 4,00,000 cases [Basu 1981]. On an average 600-1,000 infants and children developed polio every day. In 1979, India introduced OPV in three-dose schedule for infants, but for one whole decade, the incidence burden did not budge [John 2003]. The inability to control polio with the three-dose OPV schedule showed the very low efficacy of OPV, corroborated by innumerable investigations in India. Vaccine efficacy was particularly low against types 1 and 3, but better against type 2 [John 1993]. Yet, the government persisted with the same vaccine and schedule, based on blind faith in the dogma, blinded to the reality [John 2003].

There are two approaches to sustained control of polio. One is to vaccinate infants before they are at risk of infection, and achieve and sustain very high vaccine coverage for every birth cohort for all times – “perpetual control”. For this purpose the Expanded Programme on Immunisation (EPI) recommends four doses of OPV by four months of age [Epidemiol Rec 1984]. The second approach is to interrupt virus transmission by intelligent vaccination tactics – “eradication” – all children are thereafter protected from infection even without further vaccination. As there is no extra-human source of poliovirus infection, eradication is feasible, and it need be achieved just once. That is the attraction of eradication. The Global Polio Eradication Initiative (GPEI) mixed the two approaches and attempted to interrupt transmission by 100 per cent coverage with multiple (mean 10-15) doses of OPV – the method of perpetual control, under which periodic type 1 polio outbreaks may be inevitable. In many country settings that approach was successful as the force of wild virus transmission was weak. On the other hand true “pulse immunisation” with OPV, designed indigenously to address the problem in settings of very high force of transmission, does not immunise every child, but shrinks the size of the “susceptible pool” sharply and

Economic and Political Weekly December 23, 2006

abruptly, in order to interfere with transmission dynamics [John 1993]. Pulse immunisation is by OPV given annually three times over two months, leaving 10 months of the year to pursue routine immunisation with all vaccines. This design was not applied in India by GPEI, but the name “pulse” was borrowed for the repetitive campaigns meant for perpetual control – that would eventually, over the years, hopefully, result in eradication. From 1999 western UP has had 46 “pulse polio” campaigns, a veritable world record.

With OPV, pulse immunisation is better than continuous immunisation; but for IPV routine immunisation is clearly the easier and better method – especially as it can be combined with diphtheria-pertussistetanus vaccine (DPT) that we want all infants to have three times at six, 10 and 14 weeks of age, the promised precondition of polio eradication. But why not both vaccines for eradication? They are not mutually incompatible –DPT-IPV by EPI and OPV by pulse immunisation would probably have achieved polio eradication more than a decade ago, at much lower cost than the present prolonged quixotic approach [John 1993].

In 1988 the world health assembly of WHO resolved to mount a global polio eradication drive with the target year of 2000. The mandate was to reach and sustain high routine vaccination coverage and thus to strengthen the EPI as preconditions for eradication efforts. The GPEI was established within the WHO in partnership with UNICEF, US Centres for Disease Control (CDC) and the Rotary International. Fund support has come from many donor agencies and countries, but each country has absorbed the in-country expenses of staff salary and of vaccination delivery systems. GPEI ignored EPI, dissociated polio vaccination campaigns from it, and the consequences are clear in UP and Bihar.

Laboratory-confirmed polio cases have declined to 66 (99.95 per cent reduction) in 2005. Earlier, 66 cases would have occurred in just two hours. Cases were confined to UP and Bihar. This is a great achievement, if the wasted time and enormous cost are overlooked. However, in 2006 there is the outbreak with 548 cases till October, spreading to other states and to Nepal and Bangladesh. Sustaining perpetual control is impossible without eradication. During the past five years the endemically infected Nigeria and India have exported infection to some 30 countries and each of them had to conduct fire-fighting immunisation at enormous cost. Global eradication is unquestionably essential for global security against polio, for human rights in health and for equity.

As of now, 189 countries are free of indigenous polio; just four are not – India, Pakistan, Afghanistan and Nigeria. In 2005, the GoI voted in favour of the new “Global Health Regulation 2005” in the World Health Assembly. Under GHR-2005, internationally reportable (mandatory category) infections are any new strain of influenza virus, pneumonic plague and wild poliovirus – the regulation becomes effective in 2007 after national governments ratify it in 2006-07. Already, Saudi Arabia has imposed the condition of pre-travel polio vaccination certification for all hajj pilgrims from India and Pakistan, starting in 2006. If India continues with wild poliovirus infection after the GHR-2005 becomes operational, the consequences can be very serious. Our trade competitors could conceivably use it against our interests – similar to the plague year of 1994, when India apparently lost business worth over Rs 8,000 crore. Polio eradication is an economic necessity.

Eradication means 100 per cent reduction. In India uninterrupted transmission continues only in western UP and in Bihar, but from there viruses seed outbreaks spreading to other states every four years. In the WHO grouping of countries in the south-east Asia region, India remains the sole straggler – every other country succeeded on the target-year 2000. A nuclear, economically advancing, wanting-to-shine, self-proclaimed incredible India: if India cannot eradicate a disease that 189 countries have eradicated, it is an incongruity in the comity of nations in the 21st century. The proposed polio eradication commission must explore how and why we came to this pass. Polio must be eradicated from India for humanitarian, human rights and economic reasons and for India’s pride and prestige (and also to avoid discrimination).

Sceptical Public Opinion

Three recent papers in widely read journals have suggested that India may not succeed, or at least not with the current tactics even if applied more vigorously [Arita, Nakane and Fenner 2006; Kimman, Boot 2006]. Isao Arita and Frank Fenner are doyens of smallpox eradication and onetime ardent supporters of polio eradication [Arita, Nakane and Fenner 2006; Roberts 2006]. They, along with Miyuki Nakane, ask if the global polio eradication goal is realistic, under the present circumstances of uninterrupted virus circulation in four countries and reintroduction into 27 countries during 2000-2005. They propose that the goal be diluted from eradication to control. Their reasons arise from the failure to achieve success even six years after the target year. Already $ 4 billion have been spent (as against the budget of two) and 1.2 billion more may be needed to conclude the programme even if eradication succeeds today. They believe that no eradication programme will be sustainable if it exceeds 10 or maximum 15 years; GPEI is already 18 years old and yet the end is not in sight [Arita, Nakane and Fenner 2006]. While their words of wisdom are sobering, from an Indian viewpoint they are disturbing and unacceptable.

A companion paper to that of Arita and colleagues describes clearly the dilemmas [Roberts 2006]. Apparently, there are many global experts who share the view, although publicly expressed only by Arita and colleagues (ibid). Ellie Ehrenfelt of National Institutes of Health (US) who knows India very well admits: “we really don’t understand why mop-ups don’t knock out the virus in these areas [in India]” (ibid). Konstantin Chumakov of USA Food and Drugs Administration and Vadim Agol of the Russian Academy of Medical Science, two recognised polio experts, worry that the GPEI is “deluding itself” with its “ever-receding deadline – always 12 to 18 months from where we are” and “[they] press on as if nothing had happened, as if it were 1988” (ibid). Agol describes GPEI as “captives of their own advertising”. According to David Heymann, head of multi-agency polio eradication effort, WHO: “Vaccination coverage in India has never been higher… and [India] conducted nine huge campaigns” in 2005 (ibid). “Vaccinators are reaching most children…many are getting six to seven doses of vaccine a year” (ibid). The polio eradication budget of the GoI in 2006 was Rs 1,039 crore. Partners like the state governments, WHO, UNICEF and Rotary International additionally spend huge amounts. The high frequency of campaigns and huge expenses are unsustainable.

Tjeed Kimman and Hein Boot of the Netherlands National Institute of Public Health and Environment concur with Arita and colleagues, but propose fresh specific

Economic and Political Weekly December 23, 2006 goals and methods [Kimman and Boot2006]. “Although polio eradication seems to be nearly reached, there is serious doubt as to whether this will ever happen” according to them (ibid). They point out the incompatibility of OPV with polio eradication and want it to be discontinued as early as possible (ibid). They “propose to strive towards a global coverage of near 100 per cent vaccination against all childhood infections using combination vaccines that contain inactivated poliovirus vaccine” (ibid). They have a cogent and compelling argument. They believe that IPV use will be inevitable globally, although GPEI may not accept the idea now (ibid). If that is the case, why do we not begin now, so that the problems of VAPP and the frequent emergence of polio outbreaks due to “circulating vaccine-derived polioviruses” (cVDPV) are pre-empted? (ibid).

Vaccine viruses in OPV are not completely innocuous – but retain residual, irreducible virulence, as WHO had warned all countries in 1982 [WHO Bulletin 1982]. India had 181 cases of confirmed VAPP in 1999, but cases are not confirmed for counting thereafter [Kohler, Banerjee, Hlady, Andrus, Sutter 2002]. Vaccinated children shed viruses in their stools for a few weeks and these viruses show progressive genetic reversion towards increasing virulence. Transmission of vaccine viruses from child-to-child is (mercifully) extremely rare (normally polioviruses infection is not faecal-oral), but when it happens the chance of genetic reversion increases [Kew, Morris-Glasgow, Landarverde 2002]. Now the virus becomes more infectious also, presumably acquiring the nasal transmission property of wild viruses. If transmission continues to “circulation” the vaccine-derived viruses become wild-like (ibid). Such viruses are called cVDPV (ibid). In 2005 there was a huge outbreak of cVDPV in Indonesia (46 paralysed, >7360 infections) and this year there were two minor outbreaks in the US and Myanmar. About two episodes occur every year.

To prevent cVDPV outbreak near-100 per cent routine OPV coverage is necessary – as OPV protects best against vaccine viruses. To intercept cVDPV, multiple OPV campaigns are necessary, with near 100 per cent coverage, perpetuating the problem without a safe exit route. Kimman and Boot think that polio cannot be “eradicated” using such a vaccine [Kimman and Boot 2006]. In contrast, IPV is completely safe and incomparably efficient. However, their plan of action may take more than a decade to eradicate polio (ibid).

The transmission of type 2 virus ceased in UP, when the average dose of OPV had reached 6-7 per child, in 1999. Clearly sufficient coverage with sufficient doses had been reached to interrupt transmission of the virus type against which the vaccine has reasonable efficacy. Immediately it was clear that the vaccine efficacy against types 1 and 3 are insufficient to interrupt transmission. When the average doses per child reached 9-10 and were sustained over three to four years, types 1 and 3 transmission ceased in most states except UP and Bihar. Immediately it was clear that the force of wild virus transmission in these two states was too high to be overcome by the same number of OPV doses that achieved success in other states. Instead of applying “epidemiological intelligence”, quixotic attack with increased number of annual campaigns – 6 (2000 and 2003), 8 (2004) and 9 (2005), were prescribed. When the outbreak occurred in 2002 the GPEI blamed it on the reduced number of campaigns in 2001 (three in 12 months, but there was a campaign each in Decembers of 2000 and 2002 making the total five in 14 months). Epidemiology had predicted an outbreak since the earlier years of outbreaks were 1974, 1981, 1987 and 1992. The interoutbreak interval had progressively shrunk from 7 to 6 to 5 years. One would expect the reverse, inter-outbreak interval increasing with heavy vaccination. Since 1997 there have been three outbreaks at intervals of four years, after wild virus transmission was severely curtailed. Obviously wild virus is the stronger immunising agent compared to OPV, but at a heavy price of high incidence of polio. OPV is much safer than wild viruses, but very weak in providing community level immunity. IPV is a known stronger immunising agent than even wild viruses [John 1993, 2003].

The average OPV doses per child reached 15 in 2005 in UP and Bihar, but the outbreak of 2006 could not be averted. A combination of six adverse factors was obvious in these states. The population density, birth rate and density of infants are very high, resulting in very high force of transmission and infection at a very young age [IJMR 2004]. In UP, 67 per cent cases are below 24 months and 31 per cent in infants, without upward shift in the age pattern of infection over the years. (I am grateful to the National Polio Surveillance Project for information in this paragraph.) This shows that in spite of many doses of OPV, the speed of wild virus transmission continues unmodified, as if children were not immunised. OPV has afforded little mucosal immunity to retard virus circulation. The third factor is of course the extremely low vaccine efficacy that allows polio in children who had consumed many doses. In UP, 89 per cent of children with polio had consumed over four doses; 64 per cent had taken more than seven doses and 50 per cent had received more than 10 doses. This problem is usually swept under the carpet – health staff have to insist that “3 doses give life-long protection”. Staff and local community leaders could not answer parents when they asked if the liquid drops was vaccine or something else given for some other purpose. The eradication programme lost the loyalty of a proportion of local leaders, staff and families themselves.

The fourth factor was the lack of contact immunisation and herd effect of OPV. Vaccine viruses did not spread – thus every child had to be reached with multiple doses of OPV. Health staff were earlier taught that the major advantages of OPV were spread of viruses and “contact immunisation” of the unvaccinated children in the neighbourhood and high herd effect (indirect protection of unvaccinated children on account of resistance to re-infection in the vaccinated). The facts baffled them but the official line was that most children were not given OPV. Thus the staff and parents were depicted as the culprits, not the vaccine. In the absence of documentation no one can count who got how many doses. Recall of mothers is notoriously unreliable especially after so many campaigns. Therefore the allegation that the coverage is low cannot be disproved.

Most Important Factor

The fifth and perhaps the most important factor was the dismally low routine vaccination coverage, the foundation and the first requirement of an immunisation tactic for eradication. Unless a reasonable number of doses reach infants as they grow in weeks and months, vaccine-induced immunity will not match, let alone overtake, the speed with which wild viruses reached them. The average number of doses below six months is the most critical measure of community immunisation [John 1993]. In UP and Bihar most infants below six months appear to have received either no dose or only one

Economic and Political Weekly December 23, 2006

dose. They need four doses through EPI and additional doses by campaigns. Not reconstructing the broken EPI was the unkindest cut of all – as if the community was being “used” instead of being helped. The community demands protection from frequent and fatal measles (and the less common diphtheria). Offering over 30 doses of unsolicited OPV during five years of the child’s life is no substitute for EPI. The average of 15 is the result of 30 offered. Almost all doses are given beyond infancy.

The sixth factor was the inadvertent alienation of the rural illiterate Muslim families. (I am grateful to local community leaders for providing me with this insight.) The 1993 and 1998 national family health surveys had clearly identified these children as the least served by the primary healthcare system and least covered with routine vaccines by EPI. Measles, whooping cough and diphtheria occur frequently among them. Obviously polio incidence would also be higher in them than others. By blaming the victims of “minority religious” reluctance to cooperate, an opportunity was provided for miscreants to actually create such a religious divide. A few fatwas were issued against polio eradication and OPV. Muslim clergy was then roped in to counter the negative propaganda and the division was deepened. Even the print media suspected a hidden agenda in the repetitive campaigns of an ineffective vaccine, and came out with adverse comments and genuinely misguided criticism of the programme.

Eradication was not the problem – the vaccine was – but eradication was opposed. None of the promised advantages of OPV – full protection with three doses, vaccine virus spread and contact immunisation, mucosal protection and herd effect – was borne out in the field [John 2001]. What is intriguing is how and why the large amount of information, all pointing in the same direction, diligently collected and repeatedly published in peerreviewed medical journals right from 1972, were disbelieved by policy-makers and their advisers [John 1993, 2003]. Such is the power of dogma on the human mind and against observed evidence [John 2001].

India’s failure was not because of lack of political commitment, but because commitment was not translated into accountability. India did not fail for want of effective intervention tools, but because the best of them was wantonly disallowed. The failure was not because of lack of funds, but spending “penny wise, pound foolish”. It appears that we spend more on polio than all other disease control programmes together. India’s failure was not because of gaps in knowledge, but because of faith in dogma instead of in epidemiology and vaccinology. Polioviruses are fixed in their ways of behaviour; GPEI and the GoI must understand the enemy and the weapons, if the war must be won. Underestimating the enemy and overestimating the firepower are sure ways to lose a war.

What Should India Do Now?

Should India give up eradication or achieve it by new tactics? Earlier I argued that India must eradicate polio whatever the cost. The alternative is worse. I have also argued that interruption of transmission must be achieved before the next anticipated outbreak year of 2010. The major flaw in the eradication plan of action that needs rectification is the lack of an organisational set-up commensurate with the enormity of the task. Every other centrally-sponsored disease control programme has technical leadership, dedicated technocracy and a hierarchy of officers and staff right down to district level – be it against tuberculosis, malaria or HIV/AIDS. In India’s war on polio there is no general, no war room. Polio eradication is the most ambitious and most expensive public health programme ever undertaken by India. The present style of preparing plans for six months at a time is unprofessional. India must have a comprehensive strategic plan for the next 10 years, with milestones and monitoring as in-built elements.

Elimination of wild polioviruses first, sustaining elimination status for a defined period, discontinuation of vaccine virus inoculation, ensuring the quick detection of cVDPV, interception of cVDPV when detected, and reaching the victory stand of eradication without any trace of poliovirus infection are the six essential milestones. Eradication must mean the zero incidence of poliovirus infection, wild and vaccine. Therefore, the continued use of OPV is incompatible with eradication [John 1993, 2003; Kimman and Boot 2006]. Tactics and tools necessary for all six stages have to be defined and designed now, not when we face any of it as crisis.

Had there been only one problem in the eradication tactics, it could have been rectified easily. There is a multitude of problems that an apex agency like a commission must set right simultaneously, not in sequence. Having wasted precious time and money, India must re-design tactics as need demands and as science dictates. Lines of control of authority must be streamlined and centre-state-district roles and responsibilities re-engineered. Routine immunisation and EPI must be quickly set right. It is important to ask how Bangladesh and Myanmar eliminated wild poliovirus transmission. Their OPV campaigns were truly supplementary to high routine infant vaccination coverage – in India also every state with reasonable routine coverage achieved success. In all other countries and in Indian states OPV showed no contact immunisation or herd effect but 100 per cent children had to be given multiple doses. EPI made the difference. In many states the low population density and consequent low force of transmission required very little force of immunisation to interrupt transmission. In UP and Bihar the campaigns are not supplementary but in lieu of EPI. That is unscientific and inefficient.

The right choice of vaccine or mix of vaccines in the revised tactics requires knowledge, wisdom and courage. There are only limited options. Should India continue to rely on OPV or should IPV be included in the programme? Since type 2 wild virus has been eradicated seven years ago, is there any rationale in continuing to give OPV containing that type? If OPV without type 2 should be used it has to be with single type (monovalent) OPV as bivalent type 1 and 3 vaccine has never been licensed anywhere in the world. On the other hand monovalent types 1 and 3 vaccines had been used in the early days of OPV in the 1960s. India has already licensed and used mOPV-1 and mOPV-3 in UP during 2005-06. Yet transmission has persisted.

Since one dose of mOPV-1 or mOPV-3 will have better type-specific efficacy than trivalent OPV (tOPV), there is logic in switching to mOPVs. Early Indian studies had shown that the effect of one mOPV dose is equal to that of 2 to 3 doses of trivalent vaccine, but confined to the specific type. Since intestinal interference will inhibit any OPV, we must anticipate that 5-6 doses of each may be needed to eliminate both viruses. In this scenario we could get rid of type 1 first and type 3 later. If two to three years are needed to eliminate one type, four to six years will be needed for both types. Is this time frame too long or acceptable? This is an important question for the commission on polio eradication to address. Will the health system be able to give five doses of mOPV to infants below six months of age?

In early 2006 the National Technical Advisory Group on Immunisation of the

Economic and Political Weekly December 23, 2006 GoI formally asked the WHO India Expert Advisory Group on Polio Eradication, to consider if IPV had a role in completing and/ orconcluding eradication and the response was in the affirmative. Consequently the drugs controller general of India has taken the bold step of registering (licensing) IPV in India for the first time in history – in June of 2006. For want of such licensing, two IPV manufacturing units – one each in the public sector and private sector – had to be closed during late 1980s and early 1990s.

The Indian Academy of Pediatrics has advocated the inclusion of IPV in the most difficult districts in western UP to start with. For that purpose the GoI has sought and obtained the promise of limited quantities of IPV as a donation by a global company. Will the health system be able to give three doses of IPV to under-six months infants without restoring EPI in UP? Studies in India had shown that even two doses of IPV (given eight weeks apart) would immunise more infants than 15 doses of tOPV. Should two doses of IPV be started in catch-up campaigns? How soon can India concentrically and centrifugally expand the area under IPV coverage, and when can the entire country be covered? Will IPV pre-empt the emergence of cVDPV as OPV is withdrawn after wild viruses are eradicated?

Will international donors continue to support India if IPV is included in the programme? Will the cost be affordable? If India fails, will not the global investment of $ 4 billion be unprotected and insecure? While I have strong views on answers to these several questions, we need national policies evolved by an empowered group instead of depending on an individual. Policies must be based on evidence and consistent with commitment on the part of GoI and GPEI. Without their leadership and commitment even the best of options will not succeed. The proposed commission on polio eradication has much work to do in a very short time.

EPW

Email: vlr_tjjohn@sancharnet.in

References

120, pp 133-35.