Nonmedical exemptions (NMEs) allowing families to opt out their children from vaccinations required for school entry may be inversely related to measles, mumps, and rubella (MMR) vaccination rates, according to a recently published study in PLOS Medicine.

The 2015 National Immunization Survey reported only 72.2% of children aged 19 to 35 months have been fully vaccinated, as per guidelines from the Advisory Committee on Immunization Practices in the United States.

An increasing amount of families choose to opt out their children from vaccinations required for school entry by obtaining NMEs based on religious or philosophical beliefs because of parental concerns about vaccine safety. As of 2016, 18 states permitted NMEs.

NME data were collected from all 18 states currently permitting philosophical-belief NMEs: Arkansas, Arizona, Colorado, Idaho, Louisiana, Maine, Michigan, Minnesota, Missouri, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Texas, Utah, Washington, and Wisconsin. State-level data were collected from state health departments and/or the Centers for Disease Control and Prevention and analyzed by school year from 2009-2010 and 2016-2017. The state NME rate is represented by the number of entering kindergartners with a documented NME out of the total kindergarten enrollments in the state.

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States with more NME students exhibited lower MMR vaccination rates. In contrast, states that have banned NMEs exhibit the highest MMR vaccine uptake and lowest incidence of vaccine-preventable diseases.

To evaluate the influence of NMEs on vaccine uptake, the Spearman correlation was calculated between state NME rate (%) and MMR vaccination rate (%) for 20 states either allowing NMEs or 3 control states prohibiting NMEs in the 2016 to 2017 school year.

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Results showed a significant inverse association between state NME rate and MMR vaccination by Spearman correlation (P =.03), and beta regression (P =.007). Similarly, calculating the correlation between state NME rate and MMR rate for all 50 US states and the District of Columbia showed a significant inverse association between state NME and MMR vaccination (P =.04).

A recent analysis showed that in at least half the 18 states allowing NMEs, the rates have begun to plateau during the last few years; however, NMEs continue to rise in at least a third of the 18 states, with no signs of slowing down. In addition, states with plateauing levels still have the potential for outbreaks. Overall, study authors conclude that, “stricter legislative action to close NMEs should become a higher priority because of the positive correlation between leniency of state vaccination policies and exemption rates.”


Olive JK, Hotez PJ, Damania A, Nolan MS. The state of the antivaccine movement in the Unites States: A focused examination of nonmedical exemptions in states and counties. PLoS Med. 15(6):e1002578.