That which does not kill us makes us strong.
—Friedrich Nietzsche (1844–1890)
One of the most widely cited quotations from the works of Friedrich Nietzsche originates in his 1878 book, Thus Spake Zarathusra: ‘That which does not kill us makes us strong.’ Whatever inference the author may have intended, he is unlikely to have had in mind an explicit reference to vaccinology. However, this nonetheless fits well the notion that we can battle with the threat from infectious disease, and other dangers, by challenging our immune systems. These challenges may be artificial, such as vaccines, or they may be naturally endemic or environmental in nature. As we have seen, the term vaccine can be applied to all agents, either of a molecular or supramolecular nature, used to stimulate specific, protective immunity against pathogenic microbes and the diseases they cause. Vaccines work to militate against the effects of subsequent infection as well as blocking the ability of a pathogen to kill its host.
Vaccination, of course, pre-dates Nietzsche; it began in the closing years of the eighteenth century. The words ‘vaccination’ and ‘immunization’ are sometimes used interchangeably, especially in nonmedical parlance; the latter is a more inclusive term because it implies that the administration of an immunologic agent actually results in the development of adequate immunity. As the definitions of ‘vaccine’, ‘vaccination’ and ‘immunization’ ...