The United Nations is pushing ahead with its massive immunization campaign across the Middle East after 17 polio cases were confirmed last month in war-ravaged Syria, AP reported. The aim is to vaccinate more than 23 million children under the age of five against polio in the next few months - the region's largest ever immunization effort. On Monday, UNICEF kicked off the second part of the $30 million campaign, which started in November. UNICEF says the push includes Syria and neighboring countries that host a large number of refugees. Inside Syria, UNICEF hopes to reach 2.2 million children, including those living in contested areas. But it warns many children remain out of reach because they are trapped in areas under siege or in parts of the country affected by the fighting.