Major newspapers/websites like New York Times, NPR, etc all have health sections. Scroll through some of the articles and read them. Obviously they are likely to have some bias, but it's a starting point to do more research and educate yourself about the subject. Med school interviewers don't expect you to know about major breakthroughs in treatment of X condition, they want you to be able to have an informed opinion about public health issues, health policy, etc that are relevant to you. If you are paying even a little bit of attention to the world around you these topics are ripe for the picking.