Colorado has a long history with opposing vaccination, and that trend is continuing, according to state and national data.
"Our current exemption rate was 5.4 percent. The national average is 1 to 2 percent," Dr. Rachel Herlihy of the Colorado Department of Public Health and Environment said.
That means more than double the number of parents in Colorado chose not to immunize their children. That's also the fourth highest percentage in the U.S.
7NEWS reporter Jason Gruenauer asked the Health Department if there was a reason to worry.
"I certainly believe that we are at risk of a vaccine-preventable disease outbreak," Dr. Herlihy answered.
For example, a Public Health Report recently found that 18 percent, nearly one in five children in Boulder County, were not vaccinated against the measles.
The State Health Department passed new regulations earlier this year to try to turn that tide. The new health department regulations, which go into effect next year, include making parents fill out vaccine exemption forms every year for their kids instead of just turning it in just once, and making school vaccination statistics public so parents can make educated choices.