FILE: In this photo illustration, vials of measles, mumps and rubella vaccine are displayed on a counter. (Photo by Illustration Justin Sullivan/Getty Images)
Nuria Sheehan is a digital strategist and writer in Chicago. She is working on a memoir.

My father was one in 5 million.

That’s the probability of getting polio after being in contact with someone who has received the oral polio vaccine. I got the vaccine as an infant. And somehow the weakened form of the virus within it managed to infect my father. He spent nine months in intensive care, eventually becoming entirely paralyzed except for one eyelid with which he agonizingly communicated with my mother. A year after I was born, he was dead.

As the debate over vaccines rages on, it’s difficult for me not to identify, at least in part, with the fears that drive parents to not vaccinate their children. While some parents cite worries over connections between vaccines and autism (a claim that has been soundly disproven) the real fear seems to come from a deeper place that is immune to scientific evidence. It is the fear of becoming that far outlying victim of improbable risk, perhaps of some vaccine-related threat this is yet unknown. I understand such a fear. I also don’t believe it is reason enough to exempt your family from the known public good of vaccinations.

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The trial that followed my father’s death framed vaccination as an individual choice. The more complicated questions about what level of risk we should accept for the sake of public health, and what acknowledgement or compensation we might expect if we become victims of that risk, were never raised.

Rather, the trial focused on informed consent. My parents hadn’t been told of the chance of getting contact polio. Would my mother have declined the vaccine had she known about the risk, the prosecution asked. My mother couldn’t say for sure. She had no way to know whether one in 5 million would have seemed relevant to her life.

The famous medical scientist Jonas Salk testified in her support, arguing that unlike his version of the polio vaccine, which contains an inactive form of the virus, the oral polio vaccine developed by Albert Sabin was too dangerous to be used widely. The Salk vaccine has since replaced the Sabin vaccine in the United States. Still, my mother lost the case.

The trial, as much as my father’s actual illness and death, eroded the little trust that she had in medical systems. I grew up with holistic medicines and very few vaccinations. When I contracted measles at age 3, while we were traveling in Northern India, I was treated by a traditional Tibetan healer. Aside from visits to the dentist, a few cases of strep throat, and one deep gash that required stitches, I never saw conventional doctors. I was generally a healthy kid who had the sort of “natural” childhood that many anti-vaccine people advocate.

At age 25, though, I contracted mumps from an unknown source. Luckily I noticed the symptoms early and was diagnosed quickly. I didn’t leave the house for a week and, as far as I know, no one else was harmed by my infection. But it would have been easy to disregard the strange swelling of my lower jaw and to continue moving normally through the world. I worked then in a building along with someone who was HIV-positive, and I shared space with friends, coworkers and strangers who may have had invisible vulnerabilities. Like some of the families connected with the Disneyland measles outbreak, I went from perceiving myself as being a victim to being a threat to others.

This dual position, as a body that is both a potential victim and a potential threat, is one we each occupy. Yet there’s a tendency — encouraged by the increasingly consumer-focused model of medicine and the overwhelming amount of information we get about dangerous diseases, foods and environments — to focus on the ways we are vulnerable. The result of this over-identification with victimhood, at least when concerning vaccines, is fear for our own safety that can blind us to the responsibility we carry for others.

In the case of the Measles, Mumps and Rubella (MMR) vaccine, the Center for Disease Control estimates that there’s a 1 in a million chance of developing a serious (though typically treatable) allergic reaction. But accepting that risk, acknowledging that medicine isn’t perfect, and choosing to protect others with our own vaccinated bodies is what we owe in return for living in a community without an immediate presence of those diseases.

The same holds true even when there’s a chance of becoming the one in five million faced with a tragedy like my family’s. Being alive in this complex and highly interdependent world means that we constantly put our lives in the hands of others. Claiming exemptions to try to opt out of this state of vulnerability provides an illusory sense of control.