In his latest book, bestselling author William A. Haseltine tells us that understanding our natural immunity to the SARS-CoV-2 virus is critical to understanding the Covid-19 pandemic and serves as a guide to what more we can do to protect ourselves. The natural immune system is what equips the body with the tools necessary to counter new threats from the microbial world and prevent severe disease. Only when these natural protections fail do we succumb to critical illness or death. How natural immunity functions has eluded our understanding-until now. Natural Immunity and Covid-19: What It Is and How It Can Save Your Life collects insights from a fast-growing body of scientific research on the next frontier of pandemic control, not just for Covid-19 but existing and future infectious diseases. We now find ourselves in a uniquely challenging stage of the pandemic, without a long-lasting vaccine and facing a virus that evolves rapidly to become more transmissible and to defeat our best attempts at prevention and treatment. Haseltine argues that one way forward is to develop drugs that strengthen our natural immune defenses and keep vulnerable populations protected and healthy against existing and future variants.