Canada has held its measles elimination status since 1998 — but medical experts say that could change in the coming weeks. We speak with Dawn Bowdish, an immunologist and associate professor of medicine at McMaster University, about what's driving the spread of measles in Canada, what it means for public health and why she thinks Canada desperately needs a National Vaccination Registry. »»» Subscribe to CBC News to watch more videos: http://bit.ly/1RreYWS For breaking news, video, audio and in-