Analysis: A long, troubling trend in immunization is just getting worse

If this all sounds uncomfortably familiar, that’s because it should.

Idaho’s childhood immunization rates, already low, fell once again last school year. The data suggests that more than 10,000 school-age children were not fully vaccinated for a host of diseases — such as measles, chickenpox, mumps and polio.

It’s a long and troubling trend, stretching back for years. But the news here is that Idaho just got what should be a stern warning. After two decades of near dormancy, measles has made an unwelcome comeback in Idaho this fall — with 10 new cases and counting.

So today, let’s talk about a few things no one really wants to think about in post-pandemic 2023: low immunization rates, infectious disease outbreaks, and what it might mean for schools.

The discouraging numbers

Idaho’s kindergarten immunization rate fell below 78% last school year — down eight percentage points from pre-pandemic levels. And that’s more or less typical. The state Department of Health and Welfare also tracks immunization rates in first, seventh and 12th grades, and these numbers fell across the board.

The immunization rate “peaked” at 82.5% for first-graders — still a far cry from a 95% “herd immunity” rate that could blunt a measles outbreak.

Meanwhile, more kids are attending school without proof of vaccination. More than 12% of kindergartners were in class on a vaccination “exemption,” and that rate has climbed by more than four percentage points during the pandemic.

Idaho has long had one of the nation’s highest vaccine exemption rates. In 2021-22, the state’s kindergarten exemption rate topped the nation, according to a January Centers for Disease Control report. One reason is that it is extremely easy to opt out. A parent doesn’t have to provide an explanation, or even fill out a form. “You could write it on a Kleenex,” said Sarah Leeds, manager of Health and Welfare’s Idaho Immunization Program.

The downward trend began before the pandemic, but the pandemic didn’t help.

For one thing, it was just more difficult for parents to get their kids an appointment for their vaccination.

For another thing, the politicization of vaccines took a toll — even the COVID-19 vaccine has never appeared on Health and Welfare’s list of recommended childhood immunizations. Misinformation hasn’t spared any vaccine — not even a durable measles vaccine with a 97% effectiveness rate. “It feels like we’re always responding to (misinformation), rather than being ahead of it,” Leeds said.

There’s another possible factor.

In 2021, in their post-pandemic session, the Legislature passed House Bill 298, which requires schools to provide parents with information about vaccine exemptions. The bill arose, at least in part, from concerns that the state might push the emerging COVID-19 vaccines. (Idaho has never included the COVID-19 vaccine on its list of recommended childhood immunizations.)

Passed with bipartisan support, the law went into effect on July 1, 2021.

And in 2021-22, the number of children attending school with a vaccine exemption increased by nearly 21%.

The measles outbreak

Health and Welfare reported one case on Sept. 20, involving an unvaccinated man who contracted measles on a foreign trip. A week later, four unvaccinated children were exposed in the man’s Nampa home.

The number of cases has now reached 10.

To put that number in perspective, Idaho has had only two measles cases in the previous two decades, and none since 2019.

As throwbacks go, this isn’t a good one.

It isn’t kid stuff either, as state epidemiologist Christine Hahn explained recently. One in five unvaccinated adults who catches measles ends up in the hospital. (The Southwest Idaho man who contracted measles on his recent foreign trip was hospitalized.) Measles can cause a pregnant woman to go into premature labor, or deliver an underweight baby.

Measles also is airborne and highly contagious. The virus remains in the air — and potent — for up to two hours. It can easily spread on a plane ride home. Or in a kindergarten classroom, where perhaps one in five students are unvaccinated. Or even more, in some pockets of the state, where anti-vaccine sentiment travels as fast as an airborne virus.

What schools — and the state — can do

To a large extent, school officials and Health and Welfare can only wait and watch. They can wait to see if the current measles outbreak is an isolated one-off, or a portent of things to come. And watch the immunization numbers get worse.

Three years after the COVID-19 pandemic, the decreasing immunization rates are “concerning” but unsurprising, Idaho School Boards Association deputy director Quinn Perry said. There’s only so much school officials can do — and they have to carry out a law that could be making matters worse.

In 2021, the ISBA testified against the bill requiring schools to provide information on exemptions, saying it would further relax immunization rules and put students and staff at greater risk. Now, Perry said, “We’re required to comply with state statute, and that’s what school leaders are doing.”

Schools do try to piece together the holes in their immunization data as best they can. That’s a big undertaking; last school year, nearly 15,000 students attended school even though their immunization records were incomplete. This number — like the opt-out numbers — continues to climb.

By gathering more data, schools can better protect their students. For example, Perry said, schools can better assess the risk for an immunocompromised student who cannot get a vaccine.

Ultimately, schools have the authority to close their doors during a disease outbreak — as illustrated, dramatically, by the COVID-19 pandemic and by more routine shutdowns during flu season. During an outbreak, schools can exclude a student who has an infectious disease, or a student “suspected” of carrying the disease.

That’s where the immunization records become a factor, especially if a measles outbreak hits a school. If a parent has turned in an exemption — or has failed to provide complete records — their child might be forced to stay home until the outbreak dissipates.

While waiting out the current, unexpected measles outbreak, Health and Welfare faces a difficult challenge in trying to reverse years of troubling immunization numbers.

The agency has to fight anti-vaccine rhetoric: “If somebody plants a seed of, ‘This vaccine might affect fertility,’ that’s a really big ‘might,’” Leeds said. But the agency also has to fight a basic reality. Because a parent can simply turn in a slip of paper and ask for an exemption, opting out is the path of least resistance. And it means health officials and school officials never exactly know who’s vaccinated and who isn’t.

None of this is new news.

And none of this is changing.

Kevin Richert writes a weekly analysis on education policy and education politics.