What's the difference between pandemic, epidemic and outbreak?

 The World Health Organization has declared COVID-19 a pandemic. This is a landmark event. As an epidemiologist listening to the steady stream of conversation around the coronavirus, I’m hearing newscasters and neighbors alike mixing up three important words my colleagues and I use in our work every day: outbreak, epidemic and pandemic. Simply put, the difference between these three scenarios of disease spread is a matter of scale.  Suite via @the Conversation