DENVER — Colorado has the worst Kindergarten vaccination rate in the country.

According to numbers from the CDC, Colorado ranks dead last in Kindergarten rates with about 11 percent of all Kindergartners not vaccinated for diseases like measles. The national average is around 6 percent.

“If measles gets introduced in the right part of Colorado we will certainly have an outbreak,” Dr. Sean O’Leary, an infectious disease expert, told FOX31 Monday.

Currently, Colorado parents can not vaccinate their child if they seek a religious, medical, or personal belief exemption. The personal belief exemption is the most popular.

“Colorado is among one of the easiest states in the country to get a non-medical exemption,” O’Leary added.

Colorado lawmakers on Wednesday will take up the first hearing on a new bill aimed at improving vaccine rates in Colorado. 

Under the measure, parents who seek exemptions will need to submit a new standardized form to local and state health departments. Non-medical exemptions will also need to be turned in in person.

O’Leary, a supporter of the bill, says making it harder for parents will result in more vaccinated children.

“There is a lot of good in this bill,” O’Leary added.

While anti-vaccinators in Colorado have called this bill a “slippery slope” supporters of increased vaccine laws had hoped lawmakers would be more aggressive this session.

“I honestly wish there was a little more to this bill,” Lindsay Diamond, an advocate for tougher vaccine laws said.

Diamond wanted the personal belief exemption eliminated.

“I think the personal belief exemption just leaves the door open for outbreaks,” Diamond said.

In February, we reported on an effort to completely eliminate the personal belief exemption. This bill does not do that. 

Sources tell FOX31 that effort failed to get enough traction among Democratic leaders, including Governor Jared Polis.