Even a small decline in vaccination rates across the United States could have significant public health and economic consequences, according to a new paper published in the journal JAMA Pediatrics by an expert at Baylor College of Medicine. Using case examples of measles–mumps–rubella (MMR) vaccination and measles virus, Nathan Lo, an MD/PhD student in the Department of Health Research and Policy at Stanford University School of Medicine worked with Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor to develop a model for estimating the number of measles cases in U.S. children and the associated economic costs under scenarios of different levels of vaccine hesitancy.

“Measles is among the most transmissible of the infectious agents for which we use vaccines,” Hotez said. “The virus has a very high basic reproductive number, meaning if a single individual has measles, he or she could infect a significant number of individuals with the disease.” “Given the current status of vaccine coverage in the U.S., very small reductions in vaccine coverage can cause a disproportionately large increase in the number of infectious disease outbreaks, the size of outbreaks, and the public–sector costs to control them,” Lo said. Hotez and Lo were particularly interested in what could happen if there is a reduction in the percentage of preschool and school–aged children who were vaccinated with the MMR vaccine.

In the model, they studied U.S. children between the ages of 2 and 11 and found that even a 5 percent reduction in coverage of the MMR vaccine resulted in a threefold increase in measles cases throughout the United States, with an additional $2 million in public sector costs.

“We did not even consider the impact of what happens when those school–aged children bring measles home and if they have siblings under the age of 1 who are not yet old enough to have their measles vaccine,” Hotez said. “This study is providing the tip of the iceberg on what could be a more extensive measles outbreak in children under the age of 1.”