A UN-led mass vaccination campaign in underway in northeast Syria’s notorious Al Hol camp complex to protect the nearly 40,000 people being detained there from a cholera outbreak.For years, Al Hol has housed Syrians, Iraqis and other third country nationals linked to – or impacted by – the country’s long civil war, which ended with the ousting of President Bashar al Assad in late November.Among those being held are hundreds of family members of alleged terrorist fighters from ISIL and other groups.