Even the brightest medical minds have fallen victim to the scientific phenomenon known as backing the wrong horse. The Dutch physician Jan Ingenhousz (1730-99) devoted much of his life to championing smallpox inoculation using the traditional variolation method. Ingenhousz adopted the technique after moving to London in the 1760s, and then travelled to Vienna in 1768 to inoculate the family of the Austrian empress Marie Theresa and subsequently introduced the method throughout Austria.⇑

Yet when he read about Edward Jenner’s revolutionary cowpox experiment in 1798 Ingenhousz was convinced it was ill conceived and dangerous. After trying to convince the young country doctor of the error of his ways …