Graphic: Heat map of county-level NME rates in 2016 to 2017
People at extreme ends of the political spectrum are most warmly embracing the anti-vaccination movement in the United States, with certain very liberal cities and very conservative rural communities reporting the nation’s highest rates of nonmedical exemptions (NMEs), according to a new study.
The findings parallel two recent Pew studies, which found that those who are most liberal and most conservative tend to believe vaccines are unsafe. But only those who are very conservative are more likely to believe that vaccination should be a parent’s choice.
According to the new study, very high numbers of NMEs were reported in “progressive” cities like Seattle, Wash.; Austin, Texas; and Portland, Ore., as well as extremely conservative Republican strongholds, such as Arizona, Idaho and Utah. High rates of NMEs were also found in Spokane, Wash.; Phoenix; Salt Lake City and Provo, Utah; and the conservative Texas cities of Houston, Fort Worth and Plano. In Michigan, the cities of Troy, Warren and Detroit also stood out for their high exemption rates, as did Kansas City, Missouri; Pittsburgh, Penn., and smaller counties in Wisconsin.
In any case, the result is the same: As a social movement of public health vaccine opposition has grown in the US in recent years, measles outbreaks have subsequently also increased. Though measles was thought to have been eliminated from the US in 2000, outbreaks of both measles and pertussis (whopping cough) have been reported in recent years “due to inadequate immunization coverage in schools,” the study found.
Consequently, the anti-vaccine movement presents a very real potential for a public health emergency, the study found. “The high numbers of NMEs in these densely populated urban centers suggest that outbreaks of vaccine-preventable diseases could either originate from or spread rapidly throughout these populations of unimmunized, unprotected children. The fact that the largest count of vaccine-exempt pediatric populations originate in large cities with busy international airports may further contribute to this risk.”
The study further noted: “Our concern is that the rising NMEs linked to the antivaccine movement in the US will stimulate other countries to follow a similar path. It would be especially worrisome if the very large low- and middle-income countries—such as Brazil, Russia, India, and China (the BRIC nations), or Bangladesh, Indonesia, Nigeria, and Pakistan—reduce their vaccine coverage. In such a case, we could experience massive epidemics of childhood infections that may threaten achievement of United Nations global goals.”
A child with an NME from the measles, mumps, and rubella (MMR) vaccine is 35 times more likely to contract measles than is a vaccinated child, the study reported. “Moreover, a child without the diphtheria, tetanus, and acellular pertussis (DTaP) vaccine is three times more likely to contract pertussis than is a vaccinated child. NMEs weaken herd immunity that protects the population at large, particularly children who are unable to get vaccinated for medical reasons. The target vaccination coverage rate to achieve the ideal herd immunity is 90 to 95 percent, depending on the infectious agent.”
However, only 72.2 percent of children aged 19 to 35 months in the US were fully vaccinated as per guidelines from the Advisory Committee on Immunization Practices, according to the 2015 National Immunization Survey.
States with higher overall NME rates do in fact have lower measles, mumps and rubella coverage in kindergarteners. The study’s detailed analysis of NMEs within each of the 18 states revealed that several counties, including those with large metropolitan areas, are at high risk for vaccine-preventable pediatric infection epidemics.
The study also found antivaccine activities “are now being established in major metropolitan areas, rendering select cities vulnerable for vaccination-preventable diseases. As noted by the recent experience in Anaheim, Calif., low vaccination rates resulted in a measles outbreak.”
At the time of that outbreak, there was an MMR vaccination rate of just 50 to 86 percent among the exposed population. In response, California’s Legislature banned NMEs effective Jan. 1, 2016 — an action previously taken in Michigan and West Virginia. Other states have taken a less extreme approach, such as requiring parents to view an educational program prior to obtaining an NME or obtain a physician’s signature.
The study found that since 2009, the number of “philosophical-belief” vaccine NMEs has risen in 12 of the 18 states that currently allow this policy: Arkansas, Arizona, Idaho, Maine, Minnesota, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Texas and Utah. Eight of the 10 leading counties by NME rates per kindergarten population are found in Idaho.
The study’s authors recommended: “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.” Such action should be coupled with increased access to vaccines and booster shots, educational programs, and awareness campaigns.
In general, the study reports, the average rate of NMEs appears to have accelerated the most between the years 2009 and 2014, with some states exhibiting a plateau over the last three years. However, in states such as Arizona, North Dakota, Ohio, Oklahoma, Texas, Utah and others, the rates of NMEs continue to climb to the present day.
“The state of the antivaccine movement in the United States: A focused examination of nonmedical exemptions in states and counties,” was written by Jacqueline K. Olive, Peter J. Hotez, Ashish Damania and Melissa S. Nolan and published in the June 12 issue of PLOS Medicine. The authors are affiliated with the Departments of Pediatrics and Molecular Virology and Microbiology in the National School of Tropical Medicine at the Baylor College of Medicine in Houston, Tex.