State health officials believe a 2014 immunization law and last winter’s high-profile measles outbreak contributed to increases in Colorado’s kindergarten immunization rates.

Last year, 73.4 percent of kindergarteners were up-to-date on required shots, up from 63.7 percent the previous year, according to an annual survey conducted by the Colorado Department of Public Health and Environment.

Although the survey has a relatively small sample size—350 children—officials say the increase is statistically significant. In contrast, a slight jump in the percentage of kindergarteners exempted from shots by their parents—from 4.6 percent to 5.4 percent—is not statistically significant.

The report detailing the new survey numbers has not yet been published, but the department provided the numbers at Chalkbeat’s request.

Stephanie Wasserman, executive director of the Colorado Children’s Immunization Coalition, said of the jump in kindergarten immunization rates, “We applaud great news like that. It’s probably a convergence of reasons. One being the unfortunate measles outbreak.”

Required kindergarten shots

There are varying dose requirements for the immunizations below. DTaP (Diphtheria, Tetanus and Pertussis)

MMR (Measles, Mumps, Rubella)

Polio

Hepatitis B

Varicella

“Anecdotally, we heard a lot of parents who would have previously delayed or refused vaccines were getting up to date.”

The multi-state outbreak, which started at Disneyland last December, was linked with 117 cases of measles nationwide, according to the federal Centers for Disease Control and Prevention, or CDC.

Diana Herrero, deputy chief of the state health department’s immunization branch, said heightened awareness about immunizations surrounding the passage of House Bill 14-1288 is also likely a factor in the rate increase.

One of the law’s key provisions, which took effect in the 2014-15 school year, required schools to release immunization and exemption rates to the public. The new mandate prompted much greater scrutiny of how well schools collect and track students’ immunization data.

“I do think House Bill 1288…prompted some schools to be a little more diligent,” Herrero said.

Wasserman said the law holds schools publicly accountable for their rates and gives parents the opportunity to advocate for better compliance.

It’s well known that Colorado has lower immunization rates and higher exemption rates than most other states. An annual state-by-state report from the CDC, which draws on Colorado’s annual 350-child survey, reveals that Colorado’s immunization rates are in the mid-80 percent range for three of the five required kindergarten shots. In many other states, the rates for those three shots are 90-95 percent, the threshold typically needed for herd immunity.

Various factors contribute to Colorado’s low immunization rates, including the fact that historically it’s been easy for parents to opt their children out of some or all shots by claiming “personal belief” exemptions. In addition, state laws requiring childhood immunization records for school entry lack teeth and haven’t been widely enforced.

School-by-school immunization compliance and exemption rates, available for the 30 largest districts in this Chalkbeat database, can provide a valuable yardstick for parents, particularly those with babies, young children or immunosuppressed family members who are more vulnerable to disease.

In 2016-17, the state health department will launch a public database of immunization and exemption rates for schools and child care facilities statewide. In preparation for that, the department will pilot the new system in December with any interested districts.

Herrero said multiple districts asked to participate in the database this year so administrators have somewhere to direct parents and the public when immunization inquiries start coming in.