A Shot in the Arm! is the history of vaccinations and the struggle to protect people from infectious disease. Beginning with smallpox - perhaps humankind's greatest affliction to date - and concluding with an overview of the COVID-19 pandemic, Brown traces the evolution of vaccines and examines deadly diseases such as measles, polio, anthrax, rabies, cholera, and influenza. The book is narrated by Lady Mary Wortley Montagu, who historically popularized inoculation in England in the early 18th century. Brown covers the science behind how our immune systems work, the discovery of bacteria, and major achievements. Brown also tackles the public and political response to vaccination throughout history.