As the world moves into the second year of the Covid-19 pandemic, SARS-CoV-2 variants are now the fundamental issue at the root of many of our questions — Will the vaccines work? Will we need new shots each year? Will the pandemic end or can we expect a renewed surge of Covid-19 cases every year, like we see with the flu?

Understanding virus variation is critical to understanding how the pandemic will unfold and how Covid-19 may continue to affect our global economy, our societies, and all of us individually. Will the current decline in new infections in the United States, for example, be permanent or a case of seasonal population immunity? These are the questions and issues at the heart of a new book by William A. Haseltine, PhD, Variants! The Shape-Shifting Challenge of COVID-19.

Dr. Haseltine has spent a lifetime studying viruses and their ability to adapt and flourish within an ever-changing environment. In Variants! Dr. Haseltine turns his focus to SARS-CoV-2, providing a general overview of how the virus is evolving, how the variants may have emerged, and what these changes may mean for the course of the pandemic. The book also includes a guide to the scientific and lay literature on SARS-CoV-2 variants, with links to those resources, as well as a collection of Dr. Haseltine’s previous writings on the subject.

As the science evolves, so too will the book itself. Variants! is a Living eBook, updated regularly with new information as it unfolds. When a reader purchases a copy of the book, either in print or online, they will receive a special passcode that will give them online access to every subsequent edition of the book, as it is released. Readers who have already purchased a copy, visit to access the newest edition.