As evidence mounts that the U.S. education system has barely started to reckon with the impact of COVID-related school closures on students with disabilities, researchers have begun estimating the number of children who should have been evaluated for special education services during the pandemic — but weren’t.

In Washington state, about 8,500 fewer children than typically expected — enough to fill 450 classrooms — in grades K-5 were identified as needing special education between March 2020 and the start of the 2021-22 school year, according to a new brief from CALDER, the American Institutes for Research’s Center for the Analysis of Longitudinal Data in Education Research. Compared to 2018-19, the identification rate was 23% lower in 2019-20 and 20% lower in 2020-21.

The findings mirror other early analyses showing substantial drops in the number of children with disabilities who began receiving crucial support during the pandemic. Using Michigan data, for example, last year researchers from the National Bureau of Economic Research found that identification rates fell by 19% in the 2019-20 academic year and 12% in 2020-21.

It’s too soon to know whether these dips mean support for the students was delayed or whether many have simply fallen through the cracks. Rates have since returned to pre-pandemic levels, with no indication the children who were not evaluated during COVID have since been identified.

Whether crucial supports are delayed or denied, the data is alarming, says Roddy Theobald, CALDER deputy director and one of the report’s authors: “There are going to be long-term consequences. At the very least, probably those students are missing out on two years of needed services. But it’s also possible that this means they will miss 13 years.”

Here are five things to know about likely implications:

Identification matters

Two decades ago, Texas education officials illegally ordered school districts to cap special education enrollment at 8.5% of students, or slightly more than half the average rate. After the policy was brought to light, economists studied the long-term impact of special education services. Among other ramifications, they found that children denied services were 52% less likely to graduate high school and 38% less likely to enroll in college than those who received special education support.

The earlier services start, the better the outcomes

Substantial evidence shows children with disabilities go on to learn more and advance more quickly when they are identified in early grades, so they can acquire the foundational skills that will set them up for future academic achievement. For example, students with reading disabilities who get specialized help in first or second grade make gains in literacy that are nearly twice as big as children who start special education in third grade. They also continue to learn at faster rates in later years.

In addition, early intervention reduces the need for intensive services in later grades.

The numbers may be an undercount

Given the number of students who stopped attending public school during the pandemic and the sky-high rates of chronic absenteeism among pupils with disabilities in the years since schools reopened, there are likely more children who need services than show up in the data, CALDER notes.

Children of color and economically disadvantaged students are likely disproportionately impacted

The Michigan researchers found the fewest students were evaluated in districts with remote schooling and concentrations of Black, Asian and impoverished families.

The data is dire, but there is little urgency about addressing the crisis

With special ed teachers, occupational and speech therapists and other specialized staff in perennially short supply, there is little evidence school systems are making up lost services for existing students, much less seeking out and evaluating kids they might have missed.

“In a situation where districts have a hard time staffing special education, workload is a real issue for special education teachers,” says Theobald. “This creates a real problem in terms of catching up. And if they do catch up, it can make for untenable caseloads for special education teachers.”

This story was produced by The 74, a non-profit, independent news organization focused on education in America.