A surge in the number of cases of polio this year in India, particularly among children, has prompted the Indian Medical Association to question India’s eradication strategies.
India has already recorded a total of 258 cases of polio this year, against only 66 in 2005. Eight states have confirmed polio cases, but most have been clustered around the district of Moradabad in the northern state of Uttar Pradesh. Health officials are worried that the outbreak is increasing the risk of further domestic and international spread of the wild polio virus.
Federal health officers have attributed the outbreak to poor delivery of vaccines by state health staff. “Vaccine coverage had dropped in this district for several months before this outbreak,” an immunisation officer with the health ministry said. “A large number of children did not receive the multiple doses that they should have.”
In a report released this week the Indian Medical Association expressed concern at the continuing circulation of the wild polio virus despite intensified immunisation campaigns over the past 10 years.
Since 1995, in addition to routine courses of immunisation with the live oral polio vaccine, the government has conducted several mass immunisation days each year on which all children below the age of 5 years are given the vaccine. Nevertheless, some children who have had several doses of the vaccine have contracted the disease.
“Virtually all cases in recent years have occurred in children who’ve received four doses of the vaccine, and nearly half [were] in children who have received 10 doses,” said Thekekara Jacob John, a virologist formerly with the Christian Medical College in Vellore, Tamil Nadu.
“The deficiency of vaccine effectiveness has been staring at us for years,” Dr Jacob John wrote in an editorial in the Indian Journal of Medical Research (2006;124:1-4).
But immunisation officials defend the use of the oral vaccine.
“This vaccine has helped 109 countries eliminate polio, and most states in India have eliminated polio with this vaccine,” said Jay Wenger, project manager with the National Polio Surveillance Project.
The Indian Medical Association has called for an independent review of the eradication effort and asked the government to release data on vaccine associated polio paralysis, a rare side effect of the live vaccine. “The numbers of vaccine associated polio paralysis have never been made public,” said Santosh Mittal, chairman of the association’s consultative group on immunisation.
The association has also asked the government to investigate the abrupt increase in the incidence of non-polio acute flaccid paralysis in children aged below 15 years from about 8000 to 27 000 cases each year. It has rejected assertions by officials of the national polio surveillance project that this rise is the result of intensified surveillance.
“Nowhere in the world do we see such numbers, and yet this has remained uninvestigated,” Dr Mittal said.
Many virologists favour the gradual introduction of the injectable polio vaccine in India. “The injectible vaccine—currently in use in many developed countries—will provide better immunity than even 10 doses of oral vaccine and does not cause vaccine associated polio paralysis,” Dr Jacob John said.
“When this injectable alternative exists it would be unethical to continue with the live oral vaccine that might be causing more polio cases—from vaccine associated polio paralysis—than the wild polio virus itself,” he said.