Undervaccination Leaving Many Children Vulnerable to Measles, Study Concludes

Findings demonstrate need to not "become complacent" about vaccination.

SAN DIEGO — Gaps in measles vaccination rates could place as many as one in eight children at risk for becoming sick from the highly contagious illness, according to an analysis of national vaccination coverage being presented at IDWeek 2015. 

The analysis of age-specific measles vaccination data from the National Immunization Survey-Teen, suggests that nearly 9 million children may be susceptible to measles, primarily because they haven’t received the measles, mumps and rubella (MMR) vaccine, or have received only one of the two recommended doses. 

In their analysis, researchers from Emory University concluded that the percentage of children immune to measles is very close to the range of 92% to 94%. Below this threshold, measles outbreaks are possible and could lead to widespread illness.

The researchers also noted that nearly one in four children aged 3 or younger are at risk, and that nearly 5% of 17-year-olds had not received any doses of the vaccine. 

Among 17-year-olds, 4.6% had received no doses of MMR. 

“Although we eliminated continuous measles transmission in the United States about 15 years ago thanks to the effectiveness of the MMR vaccine and robust vaccination rates, these study results show that we can’t get complacent,” Robert Bednarczyk, PhD, lead author of the study and assistant professor in the Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, said during a media event about the findings. “While we currently have overall immunity in the population that should prevent sustained measles transmission, if the virus is introduced, there is the potential for large outbreaks.” 

All children should receive two doses of measles-containing vaccines at the recommended ages, he said. He noted that the biggest concern is children who haven’t received any doses for any of a variety of reasons, including: lack of access, being unaware of the need for vaccines and being opposed to vaccines. 

Dr Bednarczyk said that many of those children who were undervaccinated could be attributed to vaccine hesitancy. 

“It’s important to remember and emphasize that the measles vaccine is very safe,” Dr Bednarczyk said. “It is very important that providers recommend children are vaccinated on the correct schedule.”


1. Bednarczyk R, Orenstein WA, Omer S. 1866. Estimating the Number of Measles-susceptible Children in the United States Using the NIS-Teen. Presented at: ID Week 2015. Oct. 7-11, 2015. San Diego.