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Dead end?

  • 30/12/2006

Dead end? CONTROVERSIES dog the viability of ‘eradication’, the nature of the vaccine, and the ways to implement the programme. But India is moving on with the oral polio vaccination (opv).

gpei experts maintain that if the virus could be rooted out in Congo (with routine immunisation at 0 per cent), in Bangladesh (with sanitary conditions similar or worse that those in India) and in over 95 per cent of India itself, it can be eradicated from up and Bihar as well. “Experience, tells us that the current outbreak will not hang on in other areas but retreat to the toughest spots in up and Bihar. That is where we must hit. There is a need for area-specific strategies. What works in West Bengal might not work in up,” Wenger says.

The Indian Academy of Pediatrics (iap) too believes that the disease can be eradicated, but suggests a slight change in the strategy of administering the vaccine. It cites data to show that the disease mostly afflicts children below two years. The data also shows that around 10 doses are needed to prevent polio. But children between 6 and 9 months cannot be administered these many doses. So, iap recommends the more expensive inactivated polio vaccine (ipv) along with opv.

But ipv use strikes a raw chord (see box: Oral: the cheaper route). It was the vaccine of choice when the programme began. But difficulty in administering it and high costs militated against its use. ipv use is slated to come up for ieag’s approval at its next meeting. In fact, Moradabad and JP Nagar had also been identified for a pilot project to introduce ipv during the January 2007 round of vaccination. But this decision has been put on hold because of the resurgence of polio this year (see ‘Prickly issue’, Down To Earth, June 15, 2004).

Oral: the cheaper route
IPV is effective, but limited. It costs a whole lot

While it has been accepted that oral polio vaccine (OPV) is more suited to meet the goal of eradication, the inactivated polio vaccine (IPV) has started getting mentioned in context to India’s polio control programme. OPV consists of a weakened strain of the wild poliovirus, which grows in the intestines and prevents the growth of the wild virus. This vaccine is easy to administer and costs just US $0.07 a dose.

The viral particles are shed in the stool for up to 6 weeks. Hence OPV is believed to lead to ‘herd immunity’, as unvaccinated individuals get exposed to the vaccine virus through the faeco-oral route. Intestinal immunity is important because those who receive only IPV can get catch the wild poliovirus; the virus can grow in their intestinal tract and spread. If all countries were to shift to IPV, the prospects for eradication would diminish sharply.

IPV doesn’t help in case of an outbreak; it requires at least two to three doses and up to three months or more before satisfactory immunity is created. With OPV, the virus begins growing immediately in the intestinal tract and provides protection within days.

The flip side to OPV is polio caused by the vaccine itself. To avoid this, nearly all developed countries have switched to IPV. Clinical trials which directly compare the two vaccines are not feasible; because OPV also creates secondary immunity.

In Egypt, a country whose challenges to polio eradication are similar to those in India, a great deal of time and money was spent trying to use IPV to accelerate the eradication programme in the 1980s and early 1990s. It was only when Egypt abandoned IPV, focused on reaching its minority children, and introduced monovalent OPV that they were able to eradicate polio.


There are others, like the Jan Swasthya Abhiyan, a network of groups working on community health, that feel that the goal of eradication is not feasible. They suggest a phasing out of the anti-polio programme and making polio vaccine a part of routine universal immunisation programme. They call for more investment in sanitation and argue for making drinking water safe. This, they feel, would protect children from more than just polio. They have evidence to back their suggestion: the polio control programme was working well as a part of the routine immunisation, before the anti-polio campaign was stepped up. The incidence of polio fell from 24,000 in 1988 to 4,800 in 1994.

“who should admit its programme has failed. This is not the Indian government’s failure. An uninfluenced group of experts should show the way forward,” says Sathyamala. The Jan Swasthya Abhiyan also doubts ieag’s neutrality, since it comprises experts from organisations promoting the vaccination programme. Vipin M Vashishtha, pediatrician in Bijnor, says: “The programme has been started, it cannot be stopped. Have a deadline and ensure that the disease is eradicated within that. If this fails, have alternative strategies in place.” He also suggests research into new vaccines. For making sense of this confusion, the government needs to show a better understanding. Political commitment is essential.

RELATED ARTICLES

• Cover Story: ‘Vaccine eloquent’
 [January 31 2006]
• Debate: ‘The jab jigsaw’
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• Debate: ‘Check the vaccine’
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