DENVER — Some students in Colorado weren't in class Monday because they missed a school vaccination deadline that requires them to either be immunized or to turn in proper exemption paperwork.

A handful of districts, like Littleton Public Schools, have recently changed their vaccination policies in hopes of getting a more thorough set of records on who is vaccinated, and which families have signed off on an exemption. 

A state law that passed in 1978 allows a school district in Colorado to tell families their kids have to stay at home if they cannot provide immunization records or paperwork that indicates they are signing off on an exemption based on religious or personal beliefs. Some students cannot be vaccinated because of medical reasons. 

Students have to stay at home until that paperwork is brought up-to-date or they are immunized, according to the law.

While some districts started enforcing the law years ago, others are just now doing it, as first reported by The Colorado Sun. The reasons vary from not knowing about the state law to self-admittedly falling behind.

Here's a look at some of the district's new policies: 

Littleton School District

Littleton Public Schools gave parents until Nov. 1 to update their paperwork. 

As of Monday, a spokeswoman for the district, Diane Leiker, said a few students were still working on compliance.

Online, the district wrote: 

Per state law and LPS board policy, students who remain non-compliant with their immunizations will be excluded from school.  Beginning November 1, 2019, students without compliant immunization records and/or exemptions will not be permitted to attend school.

Boulder Valley School District

A similar deadline is coming up for Boulder Valley School District students on Dec. 2.

By that date, families have to provide one of the following documentations: 

(1) a current certificate of immunization

(2) a valid statement of exemption from immunization

A spokesman for that district, Randy Barber, said they want to remain respectful of their parents in a community where, he said, there's a strong contingency of families who aren't comfortable with vaccinations. 

Barber said they aren't encouraging parents to make one decision over the other, just that they need to know if children are vaccinated or if families are signing off on an exemption. 

For the first time, the district said kids would be told to stay home if their paperwork isn't up to date this year. 

Barber said the district realized they were a little too relaxed in enforcing the state law but increased their efforts last spring, especially because of the national conversation around immunization and measles outbreak.

Brighton 27J

The district changed its policies three years go when they first found out about the new laws. 

The first year, as many as 400 kids had to temporarily sit out of class until their paperwork was updated. Now, Haley Houtchens, a nurse with the district, said that number has dropped to less than 100. 

She also said that enforcing the new rules was tricky at first.

Hurdles in enforcement

Dr. Sean O'Leary is a pediatric infectious disease specialist with Children's Hospital Colorado. 

He said funding can be a hurdle and that some schools can only afford a school nurse once a week. He also mentioned that schools strive to keep kids in class. 

There are also concerns from families who aren't comfortable or are against vaccinations.

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There, too, is an issue of timing for families to get to the doctor. 

"I think that's one of the issues around these schools enforcing this, is trying to understand how many of these exemptions are actually exemptions to vaccinations versus they just haven't had time to get their vaccines," O'Leary said.

He added some people don't go to the doctor every year and access to primary care providers can be limited in some parts of Colorado. 

Colorado is near the bottom of a Centers for Disease Control vaccination list, with some of the lowest vaccination rates in the country.

The Colorado Department of Health and Human Services said they've left enforcement to individual schools and districts. 

In an e-mail, Acting Chief Medical Officer Dr. Daniel Shodell said:

"It is up to individual schools to ensure all enrolled students have an up-to-date certificate of immunization or exemption on file. The Colorado Department of Public Health and Environment must rely on schools to follow the immunization law. When the department or a local public health agency is conducting a disease outbreak investigation at a school for a disease for which an immunization is required, state law authorizes the department or local public health agency to prohibit any student who cannot document a current immunization for that disease from attending school for the duration of the outbreak."

Keeping accurate data is important for the district, according to the state department of health, because other kids who may not be able to get vaccinated because of medical reasons and need to know what diseases they may potentially be exposed to. Keeping accurate records is also a part of state requirements.

State legislators in Colorado tried to make it tougher for parents to skip vaccines last year but ran into resistance from Democratic Gov. Jared Polis and conservative lawmakers.

Democratic Rep. Kyle Mullica, from Adams County, introduced a bill during the legislature that would have made it harder for parents to opt their children out of vaccinations. Lawmakers abandoned the proposal a few days before the legislature ended in early May.

RELATED: With time short, Colorado lawmakers abandon vaccination bill

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