How does the author employ metaphor in the memoir, On Immunity?

Eula Biss uses metaphors throughout On Immunity. She makes many references to vampires as blood suckers who depend on the blood of others to live. Metaphorically, the health of a child is dependent on an external element beyond “self” to be healthy and safe from deadly infection.

In 1881 a handbill called, “The Vaccination Vampire” warns that vaccinations pollute babies. The use of vampires drove home the risk to parents by interjecting the imagery of the undead. There were also hints that there was a sexual element to vaccination and that the diseases that the vaccinations were designed kill were sexually transmitted. Doctors were even thought to be part of the dark conspiracy since they profited from vaccinations.

In the introduction to her book, Illness as Metaphor, Susan Sontag wrote that everyone resides in the kingdom of the well and in the kingdom the sick. Although the latter kingdom is avoided at all cost, efforts to reject it will ultimately fail. Sontag was speaking from personal experience; she was being treated for cancer at the time of this writing.