State Vaccination Policies Strong Predictor of Disease Outbreaks

University of Georgia (UGA) researchers claim lenient state vaccination laws led to epidemics of otherwise preventable diseases.

David Bradford, the Busbee Chair in Public Policy at UGA School of Public and International Affairs and Anne Mandich, PhD candidate in the Department of Applied and Agricultural Economics at UGA, claimed that despite officials declaring immunizations are important to public health there is a large portion of Americans that still forego the measure.

For their study published in Health Affairs, the team looked at state vaccination laws linking it to increased incidences of infectious disease. Using the Centers for Disease Control and Prevention (CDC)’s annual school assessment reports, the team also looked at this trend in regards to state kindergarten vaccination exemption laws and 2002 to 2012 state vaccination exemption rates.

Investigators found that policies in which health department clearance was necessary for a nonmedical vaccination exemption and penalized individuals who didn’t comply with immunization requirements resulted in a decrease in vaccine exemptions.

“Our exemption law effectiveness index identified eighteen states with the most effective [vaccination] laws and nine states with the least effective ones. The most effective states had lower incidences of pertussis, compared to other states,” the authors wrote.

The team noted that overall exemption prevalence has skyrocketed in the last decade mainly due to religious and philosophical reasons (nonmedical). According to a UGA press release, 47 states allow these types of exemptions with 39 states using a standardized exemption form.

Regarding pertussis, the researchers identified 48,000 cases were in kindergarteners in 2012. In contrast, the CDC recorded an average of 60 cases of measles per year from 2001 to 2012 compared to approximately 60 annual measles cases from 2001 to 2012.

"We need to be over 95% vaccinated to reach herd immunity," Bradford said. "For medical reasons, there a number of people who can't get vaccinated. If you can be vaccinated and are not, that's when we start to see whooping cough and measles cases rise."

The authors highlighted three policies that decreased whooping cough prevalence: state health department approval for nonmedical vaccination exemptions; making exemptions not apply to all vaccines; and implementing civil and criminal penalties for vaccination noncompliance.

"We are seeing a significant association between pertussis rates and vaccination exemption," Bradford said. "States with stricter policies have lower pertussis rates, which shows that policymakers do have it within their power to further limit the spread of these diseases."