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In at least 34 states, Covid-19 test positivity rates are higher among older children between the ages of 12 and 17 than any other age group, according to a CNN analysis of the latest Covid-19 Community Profile Report published by the federal government.

On average, test positivity rates among the 12-17 age group were more than double state rates over the past week, the federal data shows. Three states did not have test positivity data by age group available.

Test positivity rates can give an indication of how widespread infection is and how it is spreading, but only if testing is broadly accessible and utilized. Among children, some say that fewer tests focused on symptomatic cases and known exposure may have driven higher positivity rates.

“Since the testing is so targeted, it stands to reason a higher proportion of the tests would be positive,” Zachary Clark, public information officer for the Idaho’s health department told CNN.

In Idaho, the test positivity rate for the 12-17 age group was nearly 12% over the past week, the fifth highest in the country and about 60% higher than the state’s overall positivity rate of about 7%. The health department is working with the education department, school board association and governor to implement CDC guidance, he said.

The federal Covid-19 Community Profile Report does not publish the number of tests reported by age group, and the US Department of Health and Human Services did not respond to CNN’s request for more information.

However, HHS on Wednesday announced a $10 billion initiative to implement Covid-19 surveillance testing in schools across the country and upcoming guidance from the US Centers for Disease Control and Prevention on appropriate use of surveillance testing in schools and other communal settings.

Last week, Danyelle McNeill, public information officer for Arkansas’s health department, told CNN that they have “no plans at this time to require routine, regular testing as screening of school kids,” despite a positivity rate among the 12-17 age group that was more than double the state rate.

However, many experts are supportive of more testing among children.

Schools should “absolutely” be testing more to help reduce community spread, says Gigi Gronvall, an immunologist and senior scholar with Johns Hopkins University.

“Lots of people thought it would be too much of a burden for children to do the self-swabbing, but children are resilient and able to learn,” she said.

In Colorado, rapid tests are already distributed to teachers, staff and select students. And some school districts encourage students and their families to test weekly through state-funded community sites, Brian Spencer, a spokesperson for the Colorado State Joint Information Center, told CNN.

But “testing isn’t going to be the only way out of here,” Gronvall says. “It needs to be testing plus masking plus improved air quality plus vaccination strategies.”

She says she hopes building a healthier infrastructure in schools is something that evolves past Covid-19.

“A holistic approach to reduce disease transmission in schools will make it a healthier environment for kids and help them learn better.”