DNA, and why this virus is so well-suited to silently infecting humans. In this compelling and well-researched account, Dr Henry incorporates a detailed and accessible discussion of both the similarities and important differences between SARS and Covid-19. He explains why this virus is spreading around the globe with such speed and identifies a peculiar characteristic of Covid-19: its ability to delay the normal human inflammatory response until the virus is well on its way to spreading. The thrust of his scientific narrative is to underscore and explain an emerging reality regarding the Covid-2019 virus: that some of us may hardly notice the infection while others will become sick and die. In this book, we discover that the emerging threat of this novel virus hinges on its ability to exploit changes to our phenotype-a consequence of our modern human lifestyle. This account by Dr. Henry provides a much-needed synthesis of scientific knowledge aimed at offering the general reader a deeper understanding of the threat that is all around us. In addition, it is the scientific background to a forthcoming volume that will outline prevention, treatment and therapy.