A new and fascinating study in the journal Pediatrics examines what happened when an intentionally unvaccinated seven-year old boy caught measles on a trip to Switzerland in January 2008 and brought it back to San Diego. Despite the city having a 95 percent immunization rate, clusters of intentional under-vaccination, particularly in upper income and private school enclaves, led to the largest outbreak of measles in the city since 1991. 839 people were exposed to the disease, which sickened 11 other children, 8 of whom were unvaccinated, apparently due to parental fears of adverse vaccine effects or the misguided belief that “natural lifestyles” would confer protection (the other three were too young to have been vaccinated). As MedPage Today reports (only an abstract of the study is available free online), the primary infected or “index” child,
“directly infected his two siblings, two classmates, and four children who were treated at the same clinic. The index patient’s sister then infected two of her classmates. One of the index patient’s classmates infected his brother, bringing the total number of cases to 12.”
What the study call’s “a vigorous outbreak response” by city health officials prevented further transmission, but it came at a cost of $176,000 or $10,000 per case, which included the cost of quarantining infants too young to be vaccinated. Unsurprisingly, MedPage Today reports a sense of alarm among doctors over the possibility that misguided fears over vaccine risks and unrealistic expectations about “natural lifestyles” will increase the size and number of unvaccinated clusters and that herd immunity will not prove a bulwark against the transmission of disease, especially to infants who haven’t yet received their vaccinations. What is most troubling is that such clusters were most likely to occur among white, well-educated, and well-to-do parents.