India expects WHO’s polio-free certification this year

The Health Department is geared up for the intensive Pulse Polio immunisation rounds to be held on January 19 and February 23, as this year’s oral polio immunisation is crucial not just for the State but for the entire country.

This is the year when the World Health Organisation (WHO) is expected to formally certify the entire South-East Asian region, including India, polio-free.

While the country has remained polio-free for the last three years, the last case of polio due to wild polio virus in the State was reported in 2000 at Kondotty, Malappuram.

Senior officials said strengthening routine immunisation (RI) was a key activity now in States, now that the country had entered the year of polio-free certification.

While the oral polio vaccine (OPV, which provides immunity from a live but weak strain of the virus) has been in use in the national immunisation schedule to prevent the transmission of virus and boost immunity, it is a fact that a chunk of private sector hospitals and paediatricians in the State have made an exclusive shift to injectible Inactivated Polio Vaccine (IPV) or dead-virus vaccine for a while now, officials pointed out.

Local immunity

“The sero-conversion rate of the IPV at the individual level is excellent but it does not provide the child local immunity. The OPV provides local or gut immunity which is very crucial in preventing the transmission of the virus. This means that while a child, fully immunised using the IPV, is protected against polio, the virus can still grow in his intestines and be shed through the faeces, posing a risk of transmission to another person in an area where the sanitation might not be proper. The IPV protects the individual but the OPV protects the community as well,” pointed out a WHO official in the State.

“We would hence appeal to all paediatricians to ensure that all children who are being administered the IPV be given the two OPV doses in this year’s Pulse Polio rounds to prevent the transmission of the virus,” she said.

She pointed to the example of Israel, which had been using the IPV exclusively for mass vaccination of its children against polio since 2005.

Israel had now launched a campaign to mass vaccinate all children under nine years using the OPV also. This became necessary after wild polio virus was detected from sewage samples.

Even though there were no clinical cases of polio in India, it showed that the virus – imported from Pakistan was continuing to persist.

The country could be soon switching over from the trivalent OPV (which contains polio type 1,2,3 viruses) to bivalent OPV (containing only type 1 and 3). The last case of polio due to polio wild virus Type 2 was reported in 1999. But it is essential that Kerala and the nation achieve a high level of protection against Type 2 virus through routine immunisation using the trivalent OPV, prior to the switch to bivalent vaccine.