Even though the press coined the nickname “Typhoid Mary” over a century ago, the sad story of Mary Mallon has become acutely relevant again over the past few months. As an asymptomatic typhoid carrier, Mallon became infamous for infecting at least 51 people — though some estimates put the tally at more than 122 — while working as a cook. In 2020, the coronavirus pandemic has led the world to examine how this kind of carrier affects infection rates.