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In this Jan. 29, 2015, photo, pediatrician Charles Goodman vaccinates 1-year-old Cameron Fierro with the measles-mumps-rubella vaccine, or MMR vaccine, at his practice in Northridge, California. (AP Photo/Damian Dovarganes)

A series of measles outbreaks in the U.S. is putting a spotlight on the state with the lowest rate of vaccinations in the nation: Colorado.

Less than 89 percent of the state’s kindergarten-aged children have received the vaccines needed to prevent illnesses such as measles, mumps, whooping cough and chickenpox — far below the national median and the 95 percent threshold needed to prevent an outbreak.

The state ranks at the bottom because the law allows parents to claim exemptions for medical, religious or personal reasons, which is “essentially the easiest exemption policy in the country,” said Dr. Sean O’Leary, an associate professor in pediatrics and infectious diseases at the University of Colorado School of Medicine. “We need to do something about it.”

A Colorado lawmaker is drafting legislation to eliminate the personal-belief exemption and make the process harder for parents to opt out. But it’s meeting an unexpected obstacle: Gov. Jared Polis.

The Democrat is making his opposition clear from the start, and the governor’s office initially told the state’s public health agency not to help lawmakers with the legislation, an extraordinary move even for a hands-on governor.

The vaccine issue is a sensitive one in Colorado, where conservatives and vaccine critics believe parents should make decisions about whether to immunize their children, but health professionals worry the state is ripe for an outbreak.

“For Colorado, for a measles outbreak, it’s not a matter of if — it’s a matter of when,” O’Leary said.

Colorado worst in vaccinations

Data from the CDC shows Colorado with the lowest rate of kindergarteners vaccinated for MMR. Click here to see a graphic of the full ranking.

In January, Denver Public Health issued a warning about measles exposure, and in February, state health officials began investigating multiple reports of mumps infections. The Colorado alerts followed a measles outbreak in Washington state that led the governor to declare a state of emergency.

“We see outbreaks happening all over the country right now,” said state Rep. Kyle Mullica, D-Northglenn. “I’d rather be proactive, than reactive on something. We shouldn’t have to wait for a kid to die, to declare a state of emergency, before we act on something.”

MORE: Jared Polis is taking a more aggressive approach to the legislature. And not all lawmakers are happy.

Colorado is home to most vaccine exemptions

Mullica, an emergency room nurse and father of three, is leading the effort to restrict exceptions to a state law that requires all children at schools and licensed child care facilities to receive vaccinations. He said he’s approaching the issue “from a student safety perspective.”

“As a dad, I want to do all we can to protect my kids, and I want to do all we can as a legislature to protect our kids,” he said. “I feel like we have to address this. We are last in the country.”

The low rates are evident in the Centers for Disease Control and Prevention report that analyzed data from the 2017-18 school year. The federal numbers also show that more parents claim exemptions in Colorado than any other state tracked.

The vast majority — 88 percent — of the annual opt outs from vaccines were attributed to the “personal beliefs” of parents. Religious reasons accounted for just 8 percent of exemptions and medical cases were less than 5 percent, according to state-level data from the same school year.

Colorado is one of 17 states that allow personal-belief or philosophical exemptions for kindergarten students, according to the National Conference of State Legislatures, which is based in Denver. All but three states have exceptions for religious beliefs.

The new legislation in Colorado — which is expected to debut as soon as next week — would eliminate the personal exemption and make the process to claim other exemptions less convenient for parents, who can file statements at a child care and school facilities.

“We are trying to figure out how to balance that … to make sure we are not impeding on people’s religious liberty, but at the same time make sure we are creating a safe environment for kids,” Mullica said.

Opposition is mounting, and that includes the governor

Even before the bill is finalized, the opposition is mounting. Earlier this month, Mullica — who said he’s received threatening messages from opponents — hosted a forum with critics that drew more than 250 people.

Capitol Sunlight: A citizen’s guide to lawmaking and lobbying in Colorado

Pam Long of Castle Rock is one of those who attended. She spoke about her 15-year-old son who suffers from a lifelong brain injury related to a rare adverse reaction to a vaccine when he was younger.

Long, who is a board member at Colorado Health Choice Alliance, an organization dedicated to protecting opt-out rights for parents, expressed concern about doctors not being willing to write medical exemptions and the lack of disclosure about potential complications from vaccines. Her older son used a personal-belief exemption.

“(Vaccines) are not immune to all the other risk pharmaceuticals have, and we in our minds want to believe they have no risk and they are effective for all people,” she said in an interview. “There is no drug that doesn’t have risk.”

State Rep. Marc Catlin, a Montrose Republican on the health committee, said he supports the personal-belief exemption.

State Rep. Marc Catlin, R-Montrose, listens during the legislative session Jan. 4, 2019. (Kathryn Scott, Special to The Colorado Sun)

“Because we are Americans, that’s the main reason,” he said. “We can’t just continue to take pieces of what people can decide for themselves, no matter what side of the aisle you sit on. We still have to be responsible for ourselves to a certain degree.”

The objection in Polis’ mind is similar. The former five-term congressman from Boulder opposed mandatory vaccinations at the federal level, even though he immunized his two children and thinks it’s the best course. And now he objects to efforts to tighten the exemptions in Mullica’s bill.

“I am concerned about low vaccine rates and how low rates can affect public health,” Polis said in a statement issued by his office. “I think there are strategies we can employ to foster greater vaccination rates, through smart policymaking and greater public awareness, but I worry that a restrictive or top-down approach may actually backfire.”

The governor’s office did not respond to questions about what other strategies Polis would suggest, nor what he meant when he said it could backfire.

Experts tell parents: “Vaccinations are incredibly safe”

California eliminated its personal-belief exemption in 2015 only to see medical exemptions for vaccines rise — often for bogus reasons and offered at a high price, a study found.

O’Leary, an expert in vaccines at the CU Medical School, said a medical exemption is necessary only for the rarest of cases. And leading authorities, such as the American Medical Association, do not support any other exceptions.

“The facts are that vaccinations are incredibly safe and that the benefits of vaccines far outweigh the risks. And most parents see that and accept that,” O’Leary said.

In many cases, he added, “the parents who take a nonmedical exemption are doing so based on misinformation, and it’s putting children at risk,” he said.

A report from the Colorado Children’s Immunization Coalition, in coordination with Children’s Hospital Colorado, found that 558 children were hospitalized in 2017 for an illness that could have been prevented by a vaccine at a cost of more than $55 million. The majority were related to the flu, but the report also noted low rates for other immunizations, such as the measles, mumps and rubella vaccine.

“I’m an ER nurse … and I have had to take care of (children) because they had preventable things,” Mullica said.

“There’s a concern about parental rights and kind of that personal liberty piece,” he added. “But you also have to bring into the equation community safety — and that has to be addressed as well.”


John Frank is a former Colorado Sun staff writer. He left the publication in January 2021.