OKLAHOMA CITY - According to the Centers for Disease Control, childhood vaccines are the best way to prevent a number of debilitating, potentially deadly diseases.
In the U.S., the vast majority of parents immunize their children for protection from more than a dozen vaccine-preventable diseases.
But, in Oklahoma, parents have a choice.
A growing number of parents are choosing to skip the shots.
For almost all Oklahoma kindergarteners, back-to-school season includes making sure your child's immunization schedule is up to date.
"I just like to keep them healthy," said Latesha Ellis, whose kindergarten daughter, Destiny just got her back-to-school shots.
The Oklahoma City-County Health Department offer affordable immunizations; for qualifying families the vaccines are free.
"It helps protect every child in their school because not every child can the vaccine," said Brittany Rainey, R.N. "The more children we have vaccinated the better chances we have of not seeing these diseases come back."
Vaccinations are required for students in Oklahoma; public school students and private school students.
The schedule of vaccines starts at just days old and culminates at a final round on a child's fourth birthday.
By kindergarten, vaccinated children are prepared to start class fully protected from a range of diseases.
"The more children that are vaccinated the less disease we will see; the less opportunity we have to see a reoccurrence of these vaccine-preventable diseases that we haven't seen in years," said Oklahoma State Department of Health Director of Vaccine Services' Lori Linstead.
But, for a growing number of children in Oklahoma, there are no back-to-school shots.
Instead, their parents file a one-page document to apply for an immunization exemption.
"It's one form; no notary necessary; no doctor necessary," said Edmond mother, Brandi Willimon. "We have a choice."
Willimon stopped vaccinating her four children years ago when her second son, Owen, suffered a vaccine-related injury.
"I took him to a neurologist and he said you need to stop vaccinating he clearly can't handle something that's going on. A lot of kids can't so don't be afraid."
Owen Willimon is epileptic.
His seizures started right after his first round of immunizations when he was just a few weeks ago.
Since then, the Willimons have decided to fight off disease without shots.
"We do a lot of vitamin C, vitamin A, sunlight. Really (we) just try to be healthy and let nature take its course with their immune system because we were born with an immune system," she said. "I'm not afraid of measles. We can treat measles. We can treat mumps. Rubella, no one really sees that either."
Even though immunizations are required for school, all 50 states allow families to opt out of required vaccines with an exemption.
Three states require a medical reason and doctor's signature; 47 states allow for a religious exemption; 17 states allow for three types of exemption including an exemption for philosophical reasons or parent choice.
In Oklahoma, we have all three types of exemptions: medical, religious and philosophical.
"The majority of our exemptions we get into the Department of Health are for personal reasons or non-medical," Linstead said. "They can claim any type of reason that they want to exempt their child from either one vaccine, two vaccines or all vaccines that are due."
In Oklahoma, exemptions for medical reasons have remained steady over the past decade.
Religious exemptions show a small uptick over the same time period.
Exemptions for personal reasons have been on the rise in the past ten years.
"(The rate) has doubled in the last ten years," Linstead said. "Our exemption rate in Oklahoma based on the kindergarten survey from 2016-17 is 1.9 percent."
1.9 percent of kindergarten students start school with an immunization exemption because they are missing at least one vaccine on the schedule.
1.9 percent is a very small number, in line with the national average for rates of vaccine exemption.
The rate in Oklahoma is well below some outliers in states which report vaccine exempted school children make up five or six percent of the student population.
Idaho, Maine, Oregon, Utah, Wisconsin, Arizona all report vaccine exemption rates at or above five percent.
"The reason somebody is choosing to opt out of vaccine is not an easy decision, and they're making that decision most likely based upon family history of vaccine injury or reaction or on research or they've weighed the risk and benefit and they've made that decision for their child," said Liza Greve of the political action committee Oklahomans for Vaccine Safety and Health Choice.
Greve believes there is a correlation between the number of parents opting out of immunizations and the growing number of vaccines now required by schools.
Chickenpox was added to the schedule twenty years ago in 1998.
Hepatitis B was added to the kindergarten requirement that same year.
Combination vaccines, which make some parents nervous, were integrated into the schedule in more recent years.
"When you start adding these new vaccines to the schedule you are going to get parents who are educated and know the risk and the benefit and decide to opt out," said Greve.
In Oklahoma, the choice is yours.
For the 2016-17 school year, the year for which the most current data is available, about 98 percent of school children came to school with all required vaccinations.
Students who are exempted may be required to stay home in the event of an outbreak at school.
The health department immunization data comes from participating public and private schools.
The State Health Department reports about 92 percent of schools participate in the voluntary survey which covers a variety of health issues, including immunization exemption rates.
The Oklahoma State Department of Health has no data for homeschool children.
According to the U.S. Department of Education, about three percent of students are homeschooled.
In Oklahoma, State Superintendent Joy Hofmeister's office has no idea how many students choose to homeschool or how many choose to immunize.
CORRECTION: The original version of this story indicated Oklahoma Parents for Vaccine & Health Choice was a non-profit organization. It is a political action committee.