Brown could be considered the format’s premiere historian for young readers; his exhaustive research is always coupled with an understanding of human motivation and an inviting, unostentatious visual style, all while connecting the past to the world we live in now. It’s never been more urgent than in his latest, which is nearly a direct sequel to his previous Fever Year (2019). He begins his look at the development of vaccines with the origin of smallpox (smallpox scars were found on the mummified remains of an Egyptian pharaoh!) and the disease’s terrifying effects through the early eighteenth century, when our charming narrator, Mary Wortley Montagu, brought the idea of inoculations from the Ottoman Empire and popularized it in England. While tracing the work of several scientists (and cows!), Brown explicates the development of vaccines for the likes of anthrax, rabies, and polio and brings readers right back around to the eradication of smallpox. He includes stops along the way to look at the social resistance to vaccinations and the occasional but deadly missteps. And we end right now, with a note of hope for our current struggle against COVID-19. Simple visual flourishes, like a page full of graves to illustrate a death toll, have real impact, and copious back matter, including a time line, bibliography, and index, make for another insightful, erudite, and engaging work.