Several US Cities Vulnerable to Measles Outbreaks Due to Declining Vaccination Rates

As an outbreak of measles in Romania has turned deadly for dozens of children, a new study has identified areas of the United States that may be vulnerable to measles outbreaks due to opposition to vaccination.

Europe reported a fourfold increase in measles cases in 2017, which European health officials have linked with dropping vaccination rates across several countries. Romania reported 5,562 measles cases last year, the highest of any European country. The World Health Organization (WHO) and the United Nations Children’s Fund (UNICEF) have reported a decline in measles vaccination there over the last decade, with the rate of infants receiving the first dose of the vaccine falling from an estimated 95% in 2006 to 86% in 2016. As such, Romanian lawmakers have recently adopted new laws requiring that parents and guardians vaccinate their children, but according to recent news reports, a deadly measles outbreak has continued in the country, and doctors there are blaming a shortage of vaccines.

Since a measles epidemic began there in 2016, Romania has reported measles in about 13,700 individuals, along with 55 deaths. Doctors say that Romanians who work abroad are bringing the virus back with them after traveling outside of the country and that celebrities in Romania have promoted vaccine hesitancy. The Centers for Disease Control and Prevention (CDC) has issued a travel health notice for Americans visiting Romania, recommending that travelers to the country make sure that they have received the measles, mumps, and rubella (MMR) vaccine.

Researchers from the Baylor College of Medicine’s National School of Tropical Medicine in Houston recently studied the growing rate of nonmedical exemptions (NME) from vaccination occurring as part of a social movement in the United States of opposition to vaccines. In their new study, published in the journal PLOS Medicine, the researchers say they’ve identified hotspots around the United States now at risk of measles outbreaks due to declining MMR vaccination coverage. Based on the 2015 National Immunization Survey, about 72% of children aged 19 to 35 months in the United States were fully vaccinated based on guidelines from the Advisory Committee on Immunization Practices. There are currently 18 states that allow NME due to philosophical beliefs, and the researchers say the practice has grown in 12 of those states since 2009.

The study team found that there is an inverse association between NME rates and MMR vaccine coverage in states that allow the exemptions, and identified several metropolitan areas with high exemption rates that could make them vulnerable to measles outbreaks. These cities include Seattle, Washington, Spokane, Washington, Portland, Oregon, Phoenix, Arizona, Salt Lake City, Utah, Provo, Utah, Fort Worth, Texas, Austin, Texas, Kansas City, Missouri, and Pittsburg, Pennsylvania. The researchers note that ending NME policies results in increased MMR coverage.

“State and local health officials now need to work with their state legislatures to close the loopholes that allow non-medical exemptions for reasons of personal belief, as was done previously in California,” said the study’s lead author, Peter Hotez, MD, PhD, in a recent interview with Contagion^®.

Authors of the study note that following the state’s measles outbreak in Anaheim, which occurred in a population with a measles vaccination rate ranging from 50% to 86%, California passed a measure banning NMEs statewide.

Dr. Hotez said that the study team is now conducting a follow-up study to investigate the social and political demographics of the urban and rural hotspot areas, to help public health officials understand the vaccine hesitancy movement.