Today, the Colorado state House passed a vaccine bill that would tighten rules for parents wanting to exempt their children from vaccine requirements.

The School Entry Immunization Bill (SB20-163), backed with bipartisan support from Sen. Kevin Priola (R-Henderson), Sen. Julie Gonzales (D-Denver), Rep. Kyle Mullica (D-Northglenn), and Rep. Dylan Roberts (D-Avon), passed with an overwhelming majority of 40-24.

The bill requires parents who want vaccine exemptions to visit either an immunization-provider for a note of exemption, or take a short online course about vaccines to obtain a non-medical exemption.

The bill also divides exemptions into two categories: medical and non-medical.

Lastly, the bill requires medical providers to use the Colorado Immunization Information System (CIIS) to compile immunization data.

Vaccine exemptions have been a source of tension lately in Colorado politics, and it’s clear why–anti-vaccine sentiments (though present in constituents in both parties) have been especially rampant in the Colorado GOP.

This is made especially clear by Colorado’s low kindergarten vaccine rate: 87 percent, according to the Centers for Disease Control and Prevention (CDC), the lowest in the country for that age group.

According to the Oxford Vaccine Group, the minimum percentage of the population needed to be vaccinated for measles in order for herd immunity to work is 90-95 percent. Right now, because Colorado falls below that threshold, the population is especially vulnerable to an outbreak of measles and other highly contagious diseases.

In Colorado tri-county-area schools alone, the kindergarten MMR immunization rates can dip as low as a meager 23.8 percent, according to data of the lowest vaccinated or unreported schools released to the Colorado Times Recorder by the Tri-County Health Department.

These low immunization rates in these counties often follow private, religious schools, charter schools, and schools in underprivileged neighborhoods.

Although the bill will require parents looking for non-medical exemptions to educate themselves first, it “is designed to get more children fully vaccinated by the time they start kindergarten by encouraging those who do not vaccinate, but who have no objections to vaccinations, to immunize their children,” according to the Colorado House Democrats.

As Coloradans experience a major pandemic, the inclination to vaccinate children has risen significantly: not only have Coloradans increased support for mandated vaccinations for children, they have also expressed increased support of the School Entry Immunization Bill from November, according to a study from Keating Research.

The bill will return to the state Senate for final approval.