CBS News medical contributor Dr. David Agus breaks down what people need to know about the coronavirus and places it in historical context. He answers questions such as how the virus spread from bats to human in China to what precautions people should take to prevent catching the virus. Talking with CBS News' correspondent Anna Werner, Dr. Agus explains whether cornavirus has become a pandemic, what disruptions the virus may cause and how this may force people to change how they think about public health.