The Unvaccinated Child: Calculating the Risks
Jody R. Murph, MD, MS, Associate Professor of Pediatrics
University of Iowa College of Medicine
Fall 2004 

Parents and pediatricians alike struggle with the fallout resulting from news reports that suggest an association between vaccines and neurological or developmental disorders. Parents, trying to make the best decisions for their children, wonder if vaccines are safe. Pediatricians, trying to help parents understand the benefits and risks of vaccines, spend more time explaining side effects, teaching parents to interpret the medical literature as reported to the public, and helping parents make sense of risk-benefit analyses.

What do you say to the anxious parent?
First, listen to, and validate, parental concerns. Then:

• Provide accurate information
• Refute misinformation
• Inform about possible adverse vaccine events
• Explain the consequences of failing to immunize

What are the consequences if a child isn’t vaccinated?
Clearly, the reason we have seen such a dramatic decline in vaccine-preventable diseases in the last century is the high rate of immunization among US children. Prior to this, every year in the US there were nearly 1 million cases of measles, 4 million cases of chickenpox, 20,000 cases of congenital rubella syndrome and more than a quarter of a million cases of pertussis.

The clear relationship between non-vaccination and increased illness continues to be apparent today. For example, in the former Soviet Union from 1989 to 1994, cases of diphtheria rose from 839 to nearly 50,000, and resulted in more than 1,700 deaths. In several European countries, a dramatic decline in MMR vaccination occurred following a controversial 1998 report in Lancet, a British medical journal. Subsequently, Ireland experienced a measles epidemic with more than 700 cases, as did the Netherlands, with more than 3,000.

Vaccination programs that result in the immunization of a high proportion of the population can foster “herd immunity,” because when disease can’t spread easily, this protects even people who aren’t vaccinated. However, some diseases require immunization levels as high as 90% to create herd immunity. When the immunization rate dips below this level, the risk increases for disease transmission in the community, even to children who have been vaccinated.

That is because no vaccine produces 100% immunity. Vaccinated people may not be immune due to failure of the vaccine to produce an immune response in the body. Sometimes vaccines are inactivated due to improper handling or storage. With some vaccines, such as that used to prevent tetanus, immunity decreases over time unless a person is revaccinated.

Immunization exemptions
All states allow medical exemptions from immunization for a child with health-related contraindications. In addition, 48 states allow religious exemptions, and 15 allow philosophical exemptions.

It is important for parents to understand that the risks associated with exemptions affect not only their child, but the people with whom their child interacts — at home, in school or child care settings, and in the community at large.

These risks are documented in a population-based, retrospective study, published by the Centers for Disease Control in 2000. This study looks at measles and pertussis cases in Colorado, a state that allows religious and philosophical exemptions.

The CDC study found that unvaccinated children were 22 times more likely to develop measles, and 6 times more likely to acquire pertussis. If unvaccinated children were in childcare or elementary school, the rate of infection increased still more: 66 times higher for measles and 16 times higher for pertussis. Every 1% increase in the number of children who weren’t vaccinated for pertussis was associated with a 12% increase in pertussis in the schools. In 2000, 476 cases of pertussis occurred in Colorado, resulting in the deaths of two infants too young to receive vaccination. These infants most likely acquired the infection from older siblings who were not vaccinated.

Consequences: An Iowa example The consequences of immunization exemption can be significant. Earlier this year in Iowa, a group of 28 students from a small private college traveled to India with two professors. A large proportion of students attending this college have non-medical vaccine exemptions. During their stay in India, six of the students contracted measles. As a result, the Iowa Department of Public Health instructed all non-immunized contacts of these infected students to stay in India for 18 days after the last possible exposure. Despite this, one non-immunized student boarded a plane and returned to Cedar Rapids. En route, he developed the symptoms of measles.

When his measles diagnosis was confirmed, the Iowa and Michigan departments of health issued press releases to alert travelers who had passed through the Detroit (where the student had changed planes) and Cedar Rapids airports. They subpoenaed passenger lists from the airline in order to warn other passengers, and issued an alert to all airport visitors and employees in both Detroit and Cedar Rapids, warning them that they had been exposed to this disease. At least three other people contracted measles. The cost has yet to be calculated for this student’s choice to refuse measles vaccination and disregard health department instructions.

Documenting immunization
Within your own health care practice, remember to document not only what you do, but also what you don’t do.

If parents refuse vaccination for their child, it is important to document in the medical record that you recommended the specific vaccine(s) and that the parent refused. You can use the AAP “Refusal to Vaccinate” form. Be sure your practice follows “best practice” guidelines for documentation. Lawsuits have occurred for failure to immunize and also for failing to use the most recent version of the Vaccine Information Statement (VIS).

In conclusion, your role as a health care provider is to help parents and young adults make informed decisions about vaccination, and to alert them to its importance in protecting the health not just of their individual child, but also the larger community.

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