Location of Measles Cases Linked to Geographies Where Non-Medical Exemptions for Vaccines Are Clustered
SummarySince the 1980s, all 50 states have used immunization requirements as a condition of school entry to protect the public’s health from vaccine-preventable diseases.
All states allow medical exemptions to these school entry requirements for immunocompromised individuals and for certain medical contradictions, such as allergies to a vaccine ingredient. However, the rise of religious and philosophical non-medical exemptions has challenged the success of school entry immunization requirements.
As of September 26, 2019, there have been 1,243 cases of measles in the US. The cases have occurred in 31 states thus far and represent the largest number of measles cases seen in the US since 1992 and since measles was declared eliminated in the US in 2000. The ongoing outbreak has also spurred legislative action from certain affected states. Maine and New York signed legislation in May and June, respectively, to remove existing non-medical exemptions from school entry requirements.
To further understand the impact of exemption laws on vaccine-preventable diseases, Avalere overlaid data from Olive, Hotez, Damania, and Nolan, 2018 and The Washington Post to identify counties, states, and regions with measles cases and non-medical exemption hot spots. Olive et al. identified hotspots where more than 400 Kindergarteners had non-medical exemptions for the 2016–2017 school year from 14 states that allow personal belief exemptions shown in navy, and The Washington Post identified counties with measles outbreaks as of May 2019, shown in orange.
Figure 1: Non-Medical Exemption Hotspots and 2019 Measles Cases in the United States
The correlation between the location of the hotspots and the measles cases seen thus far in the US show how geographic clusters of non-medical exemptions contribute to vaccine-preventable disease outbreaks. Notably, although California removed all non-medical exemptions in 2015, an increase in individuals seeking medical exemptions and remaining pockets of unvaccinated individuals has left communities in the state vulnerable to outbreaks, as reflected in the map.
While most state legislatures have concluded their 2019–2020 sessions, interest in updating school entry legislation may continue into 2020.
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