Stronger Measles Vaccination Exemption Policies Reduce the Likelihood of an Outbreak

Strengthening a state’s policies on nonmedical vaccination exemptions could significantly reduce the likelihood of a measles outbreak, according to a new study from the University of Colorado Anschutz Medical Campus in Aurora, CO.

The study, led by Melanie Whittington, PhD, a Research Instructor in the CU Skaggs School of Pharmacy and Pharmaceutical Sciences, found that states with weaker nonmedical exemption policies could reduce their risk of a measles outbreak by 140% to 190% by making these exemptions slightly more difficult to obtain.

The study was conducted using mathematical models that simulated the magnitude of an outbreak, its likelihood, and its associated costs under three different exemption policy categories: easy, medium, or difficult.

Under the policies the researchers designated as easy, parents only needed to sign a standardized form. With the medium level of difficulty, parents were either required to attend an education session on vaccination or retrieve a special form from a health department. Policies that were designated as difficult included those that required the parents to get the form or their statement of objection notarized.

Researchers found that the level of difficulty of a nonmedical exemption policy had a significant effect on the likelihood of a measles outbreak. Those policies designated as easy had a 140% increased likelihood of developing an outbreak compared to medium policies and a 190% increased likelihood compared to difficult policies, respectively. The study also found that states could reduce the magnitude of an outbreak in half by increasing the difficulty of the policy.

"Are we really asking that much of our society to require a notarized signature rather than just somebody signing something?" asked Jonathan Campbell, PhD, Associate Professor of Clinical Pharmacy at CU Skaggs and the study's senior author. "Is that really that much of an additional effort to ask of our society to, for example, nearly halve the likelihood of a measles outbreak?"

These findings come at a time when many states are struggling with the impact of a disease that was thought to be eliminated in the United States but persists because some parents have opted out of vaccination for nonmedical reasons.

According to data from the CDC, there were 23 measles outbreaks in the United States in 2014, including one large outbreak in Ohio that resulted in 383 separate cases.

Campbell said he hopes this latest research can help change the dialogue at the policy level and provide a base of evidence that can help inform policy decisions. "Let's create a space for dialogue, let's create a space where people wrestle with evidence, and then hopefully make the best decision for either themselves or the population that they are representing," he said.