Book excerpt: Since the identification of the first cases of the coronavirus in December 2019, there has been a significant amount of confusion regarding the origin and spread of the so-called 'coronavirus', SARS-CoV-2, and the cause of the disease COVID-19. Conflicting messages from the media and officials across different countries and organizations, the abundance of disparate sources of information, unfounded conspiracy theories on the origins of the virus, unproven therapies, and inconsistent public health measures, have all served to increase anxiety in the population. Where did the virus come from? How is it transmitted? How does it cause disease? Is it like flu? What is a pandemic? In this concise and accessible introduction, a leading expert provides answers to these commonly asked questions. This revised and updated edition now also covers how the virus mutates, how important these mutations are, how vaccines work, and what we can expect in the near and long-term future.