ISLAMABAD: The health authorities have discovered that more than 78 per cent of confirmed polio cases in Pakistan involved children who had been administered polio drops.

According to a report compiled by polio eradication section of the National Institute of Health, out of 136 polio cases reported this year, 107 children had been administered polio drops on several occasions under a prescribed schedule.

The data available on the website of the World Health Organisation also indicated that Pakistan had registered the highest number of polio cases in a decade this year.

Officials in the National Polio Control Programme said that the number of polio cases had increased during the last three years after going down for the previous seven years.

They suspected that the vaccine might have lost its efficacy after not having been stored at the required temperature, especially in far-flung areas where electricity supply is disrupted for long hours.

Prof Athar Niaz Rana, head of allergy and immunology department at the Shifa International Hospital, told Dawn: “Vaccine failure and failure to vaccinate are two important factors which have affected the national polio campaign.”

He insisted that “security situation in Khyber-Pakhtunkhwa is also one of the factors which has led to the failure of vaccine in that region.”

Dr Rana pointed out that “the problem of vaccine storage in areas where refrigeration facilities are not available or power supply is discontinued very frequently also affects the efficacy of polio vaccine”.

A health ministry official told Dawn: “It is a WHO-tested vaccine and we have no doubt about its efficacy, although we have a few issues at the district level related to management.”

He said the vaccine was not being used in Pakistan alone but also in several other countries.

“A surge in polio cases in a few areas is because of security reasons and the ministry has developed a comprehensive plan for 2011 to meet the challenge.”