This refers to a very timely editorial entitled ‘Setback in Polio Eradication in India in 2002: Reasons and Remedies’ by Drs. T. Jacob John, Naveen Thacker and Jagdish M. Deshpande(1).

Some of their observations are correct, but some observations need clarification, while some issues have been left out in the editorial. Their observations suggest inadequate vaccine coverage and non-vaccination are reasons for increase in number of polio cases in the year 2002. The authors had also indicated that OPV vaccine has not made much impact. In case OPV vaccine had made any major impact, the median age of polio cases would have moved upwards. The incidence of polio has declined, but there are three contributing factors (i) OPV vaccination, (ii) immunity provided by wild polio viruses circulating in the community and (iii) improvement in hygiene and sanitation during this period, leading to less exposure to infection.

After initiation of AFP surveillance all the data related to polio are being provided by NPSP and so it happens to be the only source of informations pertaining to polio incidence in India. This author had studied AFP line lists from Rajasthan for the years 2000, 2001 and 2002. The study of these line lists shows that there have been misclassifications of AFP cases, and many compatible polio cases and VAPP cases had been discarded as non-polio cases, thus the authorities were under the impression that polio in Rajasthan was under control and would soon be eradicated. According to NPSP there were fifteen compatible polio cases in Rajasthan in year 2000, but study of line list showed that there were 58 polio cases in year 2000 in Rajasthan, but all had been discarded as non-polio cases(2).

Lack of hundred percent vaccine coverage is one of the reasons for failure of the eradication program, but not the only reason for failure to eradicate polio, in that case only un-vaccinated and partially vaccinated children would have developed polio. Vaccine failure is the main hurdle in polio eradication.

Increasing the vaccine coverage may bring down further the number of polio cases, but, polio can not be eradicated unless reasons for vaccine failure are found, because cases will continue to occur because of vaccine failure.

Polio can be caused by wild polio virus or mutant neurovirulent polio virus in OPV, called vaccine associated paralytic polio (VAPP). Although incidence of VAPP is extremely low but the incidence can be higher because of (i) vaccine failure and (ii) when OPV is given to immunocompromized children whether due to disease or drugs. The incidence of vaccine failure is high and on rise in India(2,3). As IPV is not available the doctors have two options–(i) not to administer OPV to immunocompromized child and let him or her be vulnerable to wild polio virus infection or (ii) administer OPV to the child and expose him or her to the risk of VAPP which is very high for these children. The learned authors have not touched the issue of VAPP in their excellent editorial.

The resurgence of wild polioviruses had shown that there had been some deficiencies in the vaccine and/or the strategy.

Yash Paul,
A -D-7 , Devi Marg,
Bani Park, Jaipur-302 016,
India