DENVER (AP/CBS4) – A proposal to make it harder to send kids to school without their vaccines was up for its first vote Thursday in a Colorado House committee.

The proposal had powerful bipartisan backers, but it sparked intense opposition from some.

READ MORE: JeffCo Public Health Seeking Court Order Supporting Enforcement Of COVID Mandates

Colorado is one of 18 states that allow parents and students to opt out of getting required vaccines if they submit a statement of exemption based on religious or personal beliefs.

The bill would require parents of students seeking a personal exemption to watch a video that discusses the benefits and risks of immunization to the student. Religious and medical exemptions would not be affected.

Sponsors said the change is needed because of whooping-cough outbreaks and other health risks that could be prevented if more pupils were vaccinated.

“Vaccine refusal results in higher rates of vaccine-preventable disease,” said the bill’s sponsor, Rep. Dan Pabon, D-Denver. “This is a public health issue. These are very serious diseases.”

Colorado has the sixth-highest rate of non-vaccinated kindergarteners in public school, some 3,000 statewide last school year, according to the U.S. Centers of Disease Control and Prevention.

“At the same time we saw an outbreak, an epidemic, of whooping cough the last two years,” Pabon said.

The measure would require school systems and child-care centers to disclose their rates of non-vaccinated children.

READ MORE: Glenwood Springs Businesses Hopeful Relief Money Can Help Them Recover From Problematic Summer

Lawmakers heard hours of testimony from parents on both sides.

“It should not be more convenient to opt out than it is to get your child vaccinated,” said Alexandra Fickenscher of Denver, a mother of two who supports vaccination and wants to see the exemption process tightened.

Lawmakers also heard from parents with heart-breaking stories of injuries caused by vaccines.

“Parents have a constitutional right to parent their children,” said Susan Lawson, whose daughter suffered brain damage after contracting encephalitis from a routine vaccine when she a year old. “I am not an uneducated woman.”

The bill would also require all licensed schools and day cares to post what percentage of their children are not vaccinated.

LINK: House Bill 1288

– By Kristen Wyatt, AP Writer

MORE NEWS: Stag Hollow Fire In Larimer County Now Fully Contained

(TM and © Copyright 2014 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2014 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)