An estimated 160,000 children in Pakistan's volatile Swat Valley in North West Frontier Province (NWFP) will probably be missed during this week's polio vaccination drive, says the UN Children's Fund (UNICEF).
"The district teams will continue to look for windows of opportunity to vaccinate the remaining children who are currently inaccessible due to the ongoing security situation," Melissa Corkum, a spokeswoman for UNICEF's polio eradication programme in Islamabad, told IRIN.
Some 40 percent of the targeted 400,000 children were at present inaccessible, she said.
Security forces have repeatedly clashed with pro-Taliban militants in various part of the scenic valley.
Corbin's comments coincide with the launch of the three-day sub-national immunization days (SNIDs) scheduled to begin on 8 April in 63 districts, targeting 18.5 million children under five.
About 43,000 vaccination teams will participate in the campaign - a collaborative effort between the government of Pakistan, the World Health Organization (WHO) and UNICEF, which will be monitored by over 500 national monitors.
"This is an important campaign in the highest risk areas of the country in the low transmission season for polio. It is important to achieve high coverage of all children under five years of age during the high transmission period of the year," Corbin said, noting it was critical that parents understood that all children needed the vaccine during supplementary campaigns even if they had been vaccinated in the past.
According to WHO, the world's success in eradicating polio, a debilitating disease mainly affecting children, depends on four countries where the virus remains endemic - India, Nigeria, Afghanistan and Pakistan.
In 2007, there were 31 confirmed cases of polio in Pakistan, including 11 in NWFP, 12 in Sindh, seven in Balochistan and one in Punjab Province.
To date there have been three confirmed cases of polio in Pakistan in 2008 - all in Sindh Province, including the towns of Hyderabad, Shikarpur and Nawabshah.
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