As the SARS-Cov2 virus emerged and spread globally in early 2020, unprecedented international efforts began to develop and test vaccines to control the devastating pandemic. This book focuses on the remarkable progress in developing vaccines, the amazing effectiveness of the early vaccines, and the challenges of delivering them to the population. To put this extraordinary progress into perspective, the history of other vaccines is presented and their roles in individual protection and protection of the community, "vaccines that protect the unvaccinated," are outlined.

The rigorous processes whereby vaccines are evaluated in distinct phases and the steps that must be met prior to obtaining regulatory approval for both vaccine safety and effectiveness are highlighted. Multiple vaccine approaches are reviewed, including new approaches such as "messenger or mRNA vaccine" that may revolutionize future vaccine development. The comprehensive models used to provide recommendations and priorities for vaccination of groups of people at risk are summarized. The book also focuses on the questions that remain unanswered after the vaccines are approved. These include duration of immunity, risk factors for vaccine failure, impact of viral evolution and variant strains, and assessment of both immediate and long-term safety. The authors also address concerns about vaccine acceptance including roll-out, access, and detailed and trusted sources of information.