“What happens to an essential medicine after the epidemic it treats has passed?” Prof. Jeremy Greene and Dora Vargha (University of Exeter) examine that question in a just-published article in The Lancet, “Grey-market medicines: diphtheria antitoxin and the decay of biomedical infrastructure.”

More so than most of its European neighbours, Spain at the turn of the 21st century thought it had relegated diphtheria to the past: the country had not seen a case of diphtheria since 1986. Not, that is, until a 6-year old boy was diagnosed with the disease in May, 2015. Although diphtheria has been a curable disease since the development of diphtheria antitoxin (DAT) in the 1890s and its widespread manufacture in the early 20th century, scarcely a month after his diagnosis, the child succumbed to this disease thought to have been largely tamed by modern medical science. 10 months later, a second child in Belgium perished after contracting diphtheria. Diphtheria is a treatable disease, but the window from rst symptoms to irreversible damage is short, and delay in treatment can diminish chances of survival. With physicians rarely encountering the disease that today causes less than 5000 cases annually worldwide, and DAT stocks being low or non-existent, these two cases point towards a larger question: what happens to an essential medicine after the epidemic it treats has passed?