Public Health Risks of Not Vaccinating Children—Reply

In Reply: Parents should be informed of the risks and benefits of immunization, including both the risks of severe adverse events related to vaccination (which have been shown in multiple studies to be rare) and the risks of not vaccinating. Pertussis and even measles infections still occur in the United States and pose risks both to the individual and to the community, especially in the setting of reduced frequencies of vaccination against these diseases. We chose to use the years 1987-1998 for the measles analysis because we had data from those years. Moreover, the relative risk of measles among vaccinated and unvaccinated children would not be affected by the outbreak period. In mentioning the 55 622 cases of measles that occurred during 1989-1991, Dr Orient highlights the threat of measles in the absence of an effective vaccination program. She incorrectly suggests that most of the 67% of vaccinated children in measles outbreaks who had an unknown exposure source were not exposed to exemptors but rather to internationally imported cases. In fact, few of these individuals were likely exposed to imported cases since these only accounted for 5% of measles cases among children in Colorado during 1987-1998 while exemptors accounted for 22% of cases. Orient also points out that the risk of disease among exemptors in our study was several times higher than that imposed by exemptors on vaccinated children. Although she asserts that the risk of measles in a vaccinated child exposed to an exemptor is small, this does not mean that it is acceptable. This risk would most likely be greater for other vaccine-preventable diseases that are more common than measles, such as pertussis, varicella, and pneumococcal diseases.