Colorado school vaccination rates drop for third year

More than one in 10 Colorado kindergarteners hasn’t had all of their required shots, erasing pre-pandemic gains in getting children immunized.

The percentage of Colorado kindergarteners who’d received their vaccinations declined in the previous two school years, but was still slightly higher than it had been in 2018. Now, that progress has been undone, and older children were actually slightly less likely to be vaccinated in fall 2022 than they were four years earlier.

Vaccination rates were up slightly for children in preschool and child care, though.

About 88% of kindergarteners, 92% of all school-aged children and 96% of those in preschool or day care were up to date on their vaccines during the 2022-2023 school year, state health officials said. Kindergartners showed a 5.2% decrease in compliance, and all school-aged children a 2.2% decrease, over the 2021-2022 school year.

Child care centers tend to be strict about vaccine compliance, and consequently have higher rates, said Heather Roth, immunization branch chief at the Colorado Department of Public Health and Environment.

It’s possible some children caught up on their shots later in the year and weren’t included, or their parents simply didn’t file the paperwork, Roth said. Still, it’s concerning to see less than 90% of kindergarteners clearly had their shots for a second year, and only 87% were protected from measles, mumps and rubella, she said.

“We’re concerned about our kindergarten rates, but that’s been true for a long time,” she said.

Measles is so contagious that about 95% of a population needs to be vaccinated to achieve herd immunity, and the virus can spread widely in under-vaccinated communities. Late last year, 85 children in Ohio were infected with the measles virus, and 36 had to be hospitalized. That was an unusually high hospitalization rate for a measles outbreak, possibly because a significant number also had another respiratory virus at the same time, according to MedPage Today.

It’s not clear how much of the decrease in immunization rates in Colorado is because people decided not to vaccinate their children, and how many haven’t caught up on care they missed during the pandemic, Roth said.

Dr. Sarah Nosal, a doctor in the Bronx borough of New York and member of the American Academy of Family Physicians board, said a similar trend is playing out nationwide.

About 2% fewer kindergarteners were vaccinated in the school year that started in 2021 than were in fall 2019, bringing the total who were fully immunized down to about 93%. That means more than 260,000 kids weren’t fully protected last year, even as more of them were able to return to their doctors after the initial pandemic disruption, she said.

“We should actually be seeing big increases, because people should be catching up,” she said.

A KFF poll in December found about 35% of parents nationwide think they should be able to decide not to vaccinate their children, even if it puts others at risk. That was up from about 23% of parents who said the same in October 2019.

Nosal said most of her patients are open to vaccination, but have concerns. Misinformation on social media plays on people’s desire to protect their children, while discouraging them from doing one of the most beneficial things they can for their kids’ health, she said, so providers they trust need to be ready to answer their questions.

“Our world is confusing,” she said. “It’s appropriate that people have questions.”

A study published in Pediatrics this month found that while only about 73% of children whose parents were surveyed before the pandemic were up-to-date on all vaccines, another 17% at least started receiving each series of shots, including about 8% who were only one shot away from being caught up. Children who had recently moved to a new state, lived in an uninsured family, or had more siblings were more likely to have started their vaccinations but not completed them. The study included children between 19 and 35 months who were representative of the country as a whole.

Dr. Matthew Daley, a pediatrician at Kaiser Permanente in Denver and one of the study’s authors, said that suggests that a significant number of parents aren’t opting their children out of vaccines, but may forget about shots while juggling other responsibilities.

“We feel like it’s important to tease those apart, because they’ve got different solutions,” he said.

The biggest thing that would increase vaccination rates is to make sure that all children have health insurance, because the program for uninsured children isn’t always easy to navigate, Daley said. Sending parents reminders, expanding the locations and hours where vaccines are offered and taking advantage of any health care visit to catch kids up also will help close the gap, he said.

While being one dose away from completing a vaccine series may not seem like a big deal to laypeople, children’s immune systems change significantly in the first years of life, Daley said. That means the final shot extends the child’s protection for years afterward, he said.

“An 18-month-old has a more robust immune system than a 2-month-old,” he said. “This is not just a bureaucratic exercise.”

Colorado kindergarteners are required to show proof of vaccination or get an exemption from shots for diphtheria, tetanus and pertussis (whooping cough); hepatitis B; measles, mumps and rubella; polio; and varicella (chickenpox).

Older children also need to show they continued to receive age-appropriate shots for diphtheria, tetanus and pertussis, while preschoolers need to be vaccinated against certain types of pneumococcal pneumonia and Haemophilus influenzae type b (a bacterial disease, despite the name’s similarity to flu).