An analysis finds that less than 90% of kids ages 19 to 35 months old have received the MMR vaccination in 17 states.

New Hampshire has the highest MMR vaccination rate for preschoolers at 96.3 percent, and Colorado, Ohio and West Virginia have the lowest at 86%, according to data based on the latest completed National Immunization Survey from 2013. No state in the Northeast was below 90%, while eight states in the South, five in the West and four in the Midwest had rates below 90%. Nationally 91.1% of preschoolers are vaccinated.

“Sadly, there is a persistent preschooler vaccination gap in the United States. We’re seeing now how leaving children unnecessarily vulnerable to threats like the measles can have a tragic result,” said Jeffrey Levi, PhD, executive director of TFAH. “We need to redouble our national commitment to improving vaccination rates.”