States that allow nonmedical vaccine exemptions are seeing an increase in the number of children entering their school years undervaccinated, leaving pockets of the country at risk for outbreaks of vaccine-preventable diseases, according to a new report.
Whereas immunization surveys reveal little change in national and state immunization rates over the last several years, the new report, published in PLoS Medicine, reveals increasing risk in specific areas where vaccine waivers have been most prevalent.1
“Although immunization rates may not have changed recently, we now have a serious problem with widespread, nonmedical vaccine exemptions in several US counties, especially in Western states in the Pacific Northwest, and Texas and the Southwest,” says Peter Hotez, MD, PhD, FASTMH, FAAP, dean of the National School of Tropical Medicine at the Baylor College of Medicine, Houston, Texas, and one of the study’s authors. “Many of these counties are now at risk for breakthrough measles and other childhood illnesses.”
Exemptions reduce herd immunity
Nonmedical exemptions are increasing in at least a dozen states, reaching “critical mass” in terms of herd immunity reductions to the point that breakthrough epidemics are possible, Hotez says.
According to the 2015 National Immunization Survey, 72.2% of children aged 19 to 35 months were fully vaccinated according to recommendations by the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (CDC ACIP). While national immunization data show that vaccination rates have not changed in recent years, the new report reveals a correlation between rates of nonmedical exemptions and vaccination rates, specifically for the measles, mumps, and rubella (MMR) vaccine.
Nonmedical exemptions have plateaued over the last 3 years, the CDC survey points out, but that was after an acceleration in most states between 2009 and 2014. The new study found that in two-thirds of the states allowing exemptions, there has been a rise in the number of kindergartners starting school without being fully vaccinated. The study also notes that nonmedical vaccine exemptions increased in 12 of the 18 states that permit such exemptions—Arizona, Arkansas, Idaho, Maine, Minnesota, Missouri, North Dakota, Ohio, Oklahoma, Oregon, Texas, and Utah—since 2009. Idaho has the highest levels of undervaccinated kindergartners, with almost 27% of incoming kindergartners in 1 Idaho county opting out of vaccinations in the 2016-2017 school year, according to the report.
Although the highest exemption rates appear to be in rural counties with smaller populations (under 50,000), the report also highlights a number of metropolitan areas with high numbers of nonmedical exemptions, including Seattle and Spokane in Washington state; Portland, Oregon; Phoenix, Arizona; Salt Lake City and Provo in Utah; Houston, Fort Worth, Austin, and Plano in Texas; and Kansas City, Missouri. In contrast, states that have ended allowance of nonmedical exemptions have seen increases in vaccine coverage. States with nonmedical exemptions had lower MMR vaccination rates overall, while states that have banned these exemptions—including California, Mississippi, and West Virginia—had the highest uptick in MMR vaccinations and lower incidence of disease outbreaks, according to the report.
The study did not reveal the reasons why parents requested nonmedical exemptions, but Hotez says he hopes the findings will spur a follow-up study that delves into social and demographic factors leading to exemption requests. Hotez also hopes that the report will inspire stakeholders and federal agencies to investigate nonmedical exemptions and their impact.
“Bottom line, the antivaccine movement in the US has become well organized and well financed, while the provaccine side lacks visibility in many states,” Hotez says. “We need to do a better job providing pediatricians on the front lines with tools and resources to help them with vaccine-hesitant parents.”
Hotez hopes the new report, and additional resources such as his new book “Vaccines Did Not Cause Rachel’s Autism: My Journey as a Vaccine Scientist, Pediatrician, and Autism Dad” (Johns Hopkins University Press; 2018), will help pediatricians realize they are not alone, and that vaccine hesitancy and refusal is a widespread and serious problem across the country.
1. Olive JK, Hotez PJ, Damania A, Nolan MS. The state of the antivaccine movement in the United States: a focused examination of nonmedical exemptions in states and counties. PLoS Med. 2018;15(6):e1002578. Erratum in: PLoS Med. 2018;15(7):e1002616.