15 Metropolitan Areas Have Large Numbers of Unvaccinated Kindergarten Students

MedicalResearch.com Interview with:
“Syringe and Vaccine” by NIAID is licensed under CC BY 2.0Melissa S Nolan, PhD, MPH
Assistant Professor of Epidemiology
Department of Epidemiology and Biostats
Arnold School of Public Health
University of South Carolina
Columbia, SC 2920

MedicalResearch.com: What is the background for this study?

Response: As the CDC says, “vaccines are one of the greatest success stories in public health”. In the US, fifteen different vaccines are currently available and recommendations are based on age group and medical indication. Estimates suggest that the US childhood vaccination program has prevented 381 million infections and avoided 855,000 deaths. Despite these astounding public health successes, a movement opposing childhood vaccinations has been growing. Medical contraindications do exist, and these children rely on others to be fully vaccinated to provide herd immunity for children that cannot get vaccinations for medical reasons. In contrast to this important vulnerable clinical population, other reasons for non-vaccination include religious and philosophical beliefs.

A major reason for philosophical belief-exemptions is based on the erroneous belief that vaccines cause autism. With philosophical-belief based non-vaccinated populations on the rise, our current study aimed to better understand why some parents seek exemptions for their children.

MedicalResearch.com: What are the main findings? 

Response: We found an increase in non-medical exemptions in twelve of the eighteen states that allow philosophical-belief based exemptions to childhood vaccinations. Additionally, we identified fifteen clusters of high non-vaccinated populations (>5% of all kindergartners) in these states. Statistical analysis verified that non-medical exemptions do in fact correlate to lack of MMR vaccination. Thus, our study identified that several hot-spots currently exist where the potential for a measles outbreak is reality.

Fifteen metropolitan areas have elevated populations of non-vaccinated kindergartners, mainly in states in the West, including, Washington (Seattle and Spokane), Oregon (Portland), Arizona (Phoenix), Utah (Salt Lake City), Texas (Austin, Denton, and elsewhere), and Missouri (Kansas City), as well as Michigan and Pennsylvania. We are currently executing a second study, a granular evaluation of what these populations have in common, so we can better target public health education campaigns aimed at increasing vaccination uptake by these communities. 

MedicalResearch.com: What should readers take away from your report? 

Response: In addition to these large cities having high counts of non-vaccinated children, we also found lower populated counties with high rates of non-medical exemptions. Our analysis identified ten counties with more than 14% of their kindergarteners un-vaccinated, with a preponderance in the state of Idaho. Our findings would suggest that anti-vaccination sentiment is not restricted to large cities, and that focal vaccine-preventable disease outbreaks among more suburban or rural communities are a potential.

As larger unvaccinated populations grow, particularly in highly mobile cities, the potential for vaccine preventable disease outbreaks grows. Of particular concern are measles outbreaks because measles is so highly transmissible and it is associated with high morbidities leading to hospitalization and sometimes permanent neurological injury or even death. 

MedicalResearch.com: What recommendations do you have for future research as a result of this work?  

Response: We hope this evidence-based study will help promote future studies aimed at understanding ways to increase public policy support for physician and community education campaigns on the benefits and clinical reasoning to vaccinate healthy children. 


Jacqueline K. Olive, Peter J. Hotez, Ashish Damania, Melissa S. Nolan. The state of the antivaccine movement in the United States: A focused examination of nonmedical exemptions in states and counties.PLOS Medicine, 2018; 15 (6): e1002578 DOI: 10.1371/journal.pmed.1002578 

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