MUMBAI: From being labelled the world's lone polio exporter in 2006 to reporting just one positive case till the eight month of this year, the polio scenario has never looked better than this for India. But celebrations are not in offing as the country is now faced with the challenge of fighting the vaccine-derived polio virus rather than the wild virus itself.
Simply put, the small quantity of the weakened polio virus present in the oral polio vaccine (to activate immune response) is the one seemingly causing polio in children now. At least, five children from Chhattisgarh, Punjab, Rajasthan, UP and MP have been struck by the vaccine-derived polio, whereas only one child from West Bengal has tested positive for the wild polio virus. The child from Chhattisgarh, who had a congenital anomaly and was highly immuno-deficient, recently died. There were 21 cases of vaccine-derived polio in 2009 that came down to 6 in 2010.
But, experts are of the view that even though cases of vaccine-derived polio are a cause of worry, it is not as scary as the wild polio virus that India has been fighting for decades. A senior official from the ministry of health and family welfare, New Delhi, told TOI, "We are aware of the vaccine-derived poliovirus cases. But, all the five cases are isolated and they do not seem to be circulating the virus in the community," the official said. He, however, admitted the virus in the vaccine can "mutate" and cause paralysis. "But, it is much easier to bring vaccine-derived polio under control," the official said.
Yet, some experts say the government should have been better prepared for such a scenario as it was alerted at least a decade back that there will be a stage when vaccine-derived virus will be a bigger danger. Former chairman of the India Expert Advisory Group Dr T Jacob John said vaccine-derived polio has a tendency to "become wild-like", and experts had informed the policy-makers about it long ago. He, however, added that India not reporting any wild polio virus from environment sampling in the last eight months is a very positive sign.
According to sources in the health ministry, deliberations are on as to how to tackle this. Since all the five cases of vaccine-derived polio are of Type II strain, there were discussions of stopping the trivalent immunizations (dosage for all three polio strains) for a while so that the Type II virus is not fed in the community. But, the idea was soon aborted thinking it could lead to an outbreak in the low-immune population. "The situation is more like a double-edged sword now," said Dr John, adding that benefits of OPV still outweigh cases of vaccine-derived polio virus.