Foreword

Living and coping with COVID 19, the second pandemic of the millennia after the 2009 influenza pandemic, has posed unprecedented challenges. The world has dealt with pandemics before. Human history has been shaped by diseases that present themselves as epidemic, endemic or pandemic diseases. We have registered pandemics since well before the Christian era, and surely, although no registries are available, they have always accompanied humankind. Some remarkable pandemics, that changed the course of history were the Black Plague in the 14^th century that killed a great proportion of the European population, and the Spanish Influenza, that occurred little more than a century ago in 1918-19, and killed well over 40 million people, although some scholars say the number of deaths might have reached more the 100 million.

Circumstances have changed and the world is quite different from what it used to be just a few decades ago. Knowledge, technology and communications have developed in an unprecedented speed in human history in the last century and especially in the last four decades. While these are great achievements, they also pose new challenges. Lifestyles have changed and the world faces global threats such as climate change, overpopulation, undernourishment, non-communicable diseases, the emergence of new potentially pandemic infectious diseases such as COVID-19, and many others that have pushed together the global community in efforts to deal with them in a coordinated fashion. Common targets such as the Sustainable Development Goals prove that leaders all over the world are concerned about the future of humankind, although not all to the same extent.

These efforts, however, have been insufficient, and COVID-19 has shown that much more thanmeetings, nice documents and good intentions are needed to face current challenges. ConfrontingCOVID-19 has risen several questions that need yet to be answered by scientists as well aspoliticians. For instance, what was the origin of SARS-CoV-2; how can we deal with health inequities such as differential access to vaccines, or why many governments and country leaders disregarded the World Health organization’s recommendations.

In this very complicated scenario, any attempt to better understand and cope with COVID-19are welcome. This book will surely provide vast and comprehensive knowledge about the pandemic and its development, and the best ways to confront it.

Editor and author, Andr´es Fraguela Collar, has brought together several contributors, fromdifferent Mexican institutions as well as from highly renowned institutions from other countries ina great effort to try to understand COVID-19.

In chapter 1, readers will find a very thorough and challenging description of the mathematicalmodelling of pandemics in general and of COVID-19, in particular. Chapter 2 will guide themthrough key issues about the epidemiology of infectious diseases. They will get a comprehensiveview from chapter 3 about what was known at the time the book was written about how SARS-CoV-2 does its damage, how we, human beings, experience the disease and where were the possible treatment options at that moment.

Chapter 4 is devoted to mathematical modelling of epidemics. Chapter 5 will offer readers avery interesting discussion about the importance of data analysis, and the challenges faced when dealing with something new like COVID-19.

Chapter 6 deals with the epidemic progression of the diseases in a nonhomogeneouspopulation. Those who love Mathematics will enjoy this chapter. Chapter 7 leads the readerthrough the very important subject of social inequities and their role in the propagation of infectious diseases.

Chapter 8 will update the reader on the statistical approach to understand the severity and fatality of COVID-19.

Chapter 9 is devoted to the Cuban experience, on immunotherapy and the role played by mathematical models of disease progression at the individual level.

Chapter 10 and last explains in a very comprehensive manner many aspects of vaccine development and the challenges it poses.

Throughout the book, the reader will find many graphs, tables and formulas, and a very extensive bibliography in each chapter.This book is an example of a multidisciplinary endeavor. It is no easy reading for those who do not have statistical or mathematical background, but anyhow it will be highly enjoyable for anyreader and particularly for those familiar with mathematical concepts and methods.

COVID-19 is evolving in many senses, and it is a challenge to health systems, and at theindividual level, to both clinicians and researchers. Modelling it has proved to be a very difficulttask and as we learn more about it, we discover that there are yet many things to unveil. With thisdisease, humankind is walking in unchartered territory.

I recommend the reader to follow on new every day developments, to stick to basic publichealth messages which have proven to be the best defense against the disease and to have in mindthat this will not be the last pandemic we will face. There is a very high probability of a newpandemic in the future, although we do not know when or how it will occur. As someone said “the clock is ticking, but we do not know what time it shows...”

Enjoy this book, as it contributes to better understand COVID-19.