Of the 98 cases of poliomyelitis detected in Bihar till October 30 this year, 93 children had been given seven doses of the oral polio vaccine (OPV), according to World Health Organisation (WHO) data made available to the Hindustan Times.
The data, collected under the WHO’s National Polio Surveillance Programme, has cast a shadow on the efficacy of the anti-polio drive in the state.
One of the children had been given three doses. The vaccination status of the other four is not known.
“Either the affected children suffer from serious immunity deficiency or the OPV has failed to produce the required immunity in them,” Bihar Immunisation Officer Gopal Krishna said.
The WHO provides technical support to the polio elimination programme. A WHO representative said in New Delhi that the proportion of children affected was minuscule.
“Of the 38 million vaccinated in Uttar Pradesh and 21 million in Bihar during each vaccination round, there is always a miniscule percentage of children in whom the vaccine may not offer protection,” said Dr Hamid Jafari, project manager, National Polio Surveillance Programme.
“This happens because of frequent infections like diarrhoea, which do not allow the vaccine to stay in their body long enough for them to develop immunity.”
But WHO data suggests that when anti-polio activity was said to have intensified in north Bihar, the incidence increased in central parts of the state. And when teams implementing the measures came to central Bihar, the number of those afflicted rose significantly in north Bihar.
In 2009, Saharsa district reported the maximum number of cases (22), followed by Khagaria (15) and Patna (13).
Dr S.P. Srivastava, former head of the paediatrics department, Patna Medical College and Hospital said the vaccine had failed to act on the changing genetic mutation of the virus.
Other doctors blamed poor sanitation and population density for the spread of polio.