Why are children developing polio even after inoculation?
Check the vaccine
The department of health and family welfare introduced the pulse polio immunisation programme in 1995. Since then, many rounds of national and sub-national anti-polio days have been observed and numerous children aged up to five administered the oral polio vaccine (opv).
However, polio continues to afflict. And, what is more terrifying, many children have developed the disease even after taking ten or more doses of opv. Why has the vaccine failed to protect? Common sense dictates that there can be two reasons. Many children might not respond to the vaccine because of some factors in their body, known as inhibitors. It is also possible that the vaccine might have been of poor quality -- a result of manufacturing flaws or bad storage facilities.
All this clearly indicates a case of vaccine failure. Some experts suggest administering many doses of the opv to take care of this . But they overlook a very unique property of opv. Unlike many other vaccines, the opv comprises live viruses. Though their virulent properties are removed, these vaccine viruses can re-acquire these properties during replication and multiplication in the gut. These mutant viruses can then cause paralytic polio, like the wild virus. In other words, vaccine failure with opv leaves children vulnerable to vaccine associated paralytic poliomyelitis (vapp). Also, mutant vaccine polio viruses can spread and cause polio in children who were not administered opv -- this is called contact vapp. Mutant vaccine viruses could be one reason for the high incidence of vapp in our country.
The deadline for polio eradication has been extended many times. Going by conventional wisdom, we should have known full well that a programme, which has not worked in nine years (1995-2003), would not eradicate polio in the tenth year (2004).
Indian experts should conduct studies to find reasons for the vaccine's poor performance -- so that some remedies can be suggested. Otherwise, the deadline for polio eradication will be extended time and again and blame for the failure of the programme will be put on those parents who have not taken their children for vaccination.
Yash Paul is a Jaipur-based pediatrician. Contact him at email@example.com
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