Eula Biss has no medical training but has two important qualifications for writing this book: she is a mother, and she has an incisive determination to probe beyond the accepted truths about immunity and all that relates to it. The book was published in 2014, with references to the H1N1 epidemic of 2009, but is hugely relevant today given the inescapable spectre of Covid. She researches the history of infections and immunisation in clear, jargon-free language, and digresses into discussions of racism, risk perception, politics, wealth disparity, belief systems, and vampires(!). In particular she investigates the standpoint of "anti-vaxxers" and points out that immunisation was once welcomed by the privileged as it protected them from the diseases of the (unwashed) masses. Now the wealthy are more likely to question vaccination, seeing their superior lifestyle as bestowing health and immunity against infection. "When we encounter information which contradicts our beliefs...we tend to doubt the information, not ourselves," sums up the attitude of many who repudiate objective findings (with regard to climate change and US election results, as well as immunity, I would guess.) This is a gem of a book, and highly recommended for anyone grappling with the dilemma of whether to receive their Covid, or indeed any other, vaccination. "The more vulnerable we feel, sadly, the more small-minded we become."