Book excerpt: In UnHealthcare, Silicon Valley entrepreneur and investor Hemant Taneja and Jefferson Health CEO Stephen Klasko, along with writer Kevin Maney, make a provocative case for a new data-driven, cloud-based category of healthcare called "health assurance." The authors show how health assurance can be built using today's technology, how it will help us all stay healthier at less cost, and how data from health assurance services can help individuals and officials contain and manage deadly virus outbreaks such as Covid-19. More than just a thesis, UnHealthcare is a guide to how entrepreneurs, healthcare professionals, and policymakers can bring health assurance to the mainstream and finally develop a solution to America's healthcare debacle.