Injectable vaccine to keep polio at bay

in the offing

It’s been three years since India achieved one of its biggest health milestones--of being polio free. But keeping the polio virus at bay in the coming years still remains an issue of concern. Hence, plans are afoot to replace the Oral Polio Vaccine (OPV) to the injectable polio vaccine (IPV) in India beginning next year. Recently, top doctors and medical professors who participated at the Ranbaxy Science Foundation’s 32nd Round Table Conference on “Lessons from the Success of Polio Elimination”, highlighted the importance of switching from the (OPV) to the (IPV) in India.

Dr T Jacob John, chairman, Child Health Foundation, warned, “Though we have successfully combated the menace of polio using oral vaccines containing live viruses, it has to be kept in mind that only the wild polio viruses have been eliminated from India, while the vaccine-derived polio viruses still remain a threat.”

He added, that IPV, planned to be introduced in 2015, “is inevitable if we have to prevent vaccine-derived cases of polio and achieve total eradication of the disease. Once IPV is launched to pre-empt circulating vaccine-derived poliovirus, we can gradually discontinue OPV, starting with type 2 component.”

According to health experts, IPV, though more expensive, carries inactive forms of all three strains (Type 1, 2 and 3) of the polio virus. It has no risk of virulence. In contrast, OPV carries live but weakened form of the virus which can give rise to occasional cases of polio, especially of the Type 2 strain, the wild counterpart of which is now absent.

Highlighting the high level of routine immunisation in all states, John said, “IPV is much more effective than OPV in a country like India when introduced in the routine immunisation program. Had we adopted IPV earlier, we could have banished polio years ago due to it having much higher efficacy than OPV. As India moves to IPV next year, it would be critical to achieve and retain high levels of immunisation.”

The success of India’s polio campaign is particularly striking since many other disease-control projects have been an abject failure. For example, TB control started in 1962, yet India even today has the world’s largest burden of TB and MDR TB. According to experts, the polio program was a success because it gave equal importance to three crucial areas of sociology, epidemiology and vaccinology.

Professor NK Ganguly, former director general, Indian Council of Medical Research, says, “For a successful rollout of IPV in the country, the Government needs to build capacity and ensure sufficient stocks and logistics. The availability of the vaccine would be a critical factor. We also need to build advocacy among the people and have trained manpower ready from the primary immunisation field to administer the injections.”
Health experts also warned against the threat of the wild polio virus infiltrating into India from Pakistan and restarting the epidemic that was eliminated recently, after a
nationwide struggle spanning decades.

“The threat of virus importation from Pakistan is very real. Though, it is now mandatory for everyone from the neighbouring country to take an additional dose of polio vaccine before entering India, measures like this can only reduce the risk, not eliminate it. The number of polio cases in Pakistan has already crossed 200 this year, the highest in more than a decade, setting alarm bells ringing. It is necessary for India to keep 100 per cent immunity status against polio, until Pakistan gets polio-free. Till that happens, we have to act as if we continue to have polio in our country,” the former director general, ICMR said.

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