On a recent Monday morning, a group of preschoolers filed into the gymnasium at Hillside School in the west Chicago suburbs. These 4- and 5-year-olds were the first of more than 200 students to get tested for the coronavirus that day — and every Monday — for the foreseeable future.

This story is part of a partnership that includes Illinois Public Radio, NPR and KHN. It can be republished for free.

At the front of the line, a girl in a unicorn headband and sparkly pink skirt clutched a zip-close bag with her name on it. She pulled out a plastic tube with a small funnel attached. Next, Hillside superintendent Kevin Suchinski led the student to a spot marked off with red tape. Suchinski coached her how to carefully release — but not “spit” — about a half-teaspoon’s worth of saliva into the tube.

“You wait a second, you build up your saliva,” he told her. “You don’t talk, you think about pizza, hamburgers, French fries, ice cream. And you drop it right in there, OK?”

The results will come back within 24 hours. Any students who test positive are instructed to isolate, and the school nurse and administrative staff carry out contact tracing.

Hillside was among the first in Illinois to start regular testing. Now, almost half of Illinois’ 2 million students in grades K through 12 attend schools rolling out similar programs. The initiative is supported by federal funding channeled through the state health department.

Schools in other states — such as Massachusetts, Maryland, New York and Colorado — also offer regular testing; Los Angeles public schools have gone further by making it mandatory.

These measures stand in sharp contrast to the confusion in states where people are still fighting about wearing masks in the classroom and other anti-covid strategies, places where some schools have experienced outbreaks and even teacher deaths.

Within a few weeks of schools reopening, tens of thousands of students across the U.S. were sent home to quarantine. It’s a concern because options for K-12 students in quarantine are all over the map — with some schools offering virtual instruction and others providing little or no at-home options.

Suchinski hopes this investment in testing prevents virus detected at Hillside School from spreading into the wider community — and keeps kids learning.

“What we say to ourselves is: If we don’t do this program, we could be losing instruction because we’ve had to close down the school,” he said.

So far, the parents and guardians of two-thirds of all Hillside students have consented to testing. Suchinski said the school is working hard to get the remaining families on board by educating them about the importance — and benefit — of regular testing.

Every school that can manage it should consider testing students weekly — even twice a week, if possible, said Becky Smith. She’s an epidemiologist at the University of Illinois in Urbana-Champaign, which developed the saliva test Hillside and other Illinois schools are using. Smith pointed to several studies — including both peer-reviewed and preliminary research — that suggest rigorous testing and contact tracing are key to keeping the virus at bay in K-12 schools.

“If you’re lucky, you can get away without doing testing, [if] nobody comes to school with a raging infection and takes their mask off at lunchtime and infects everybody sitting at the table with them,” Smith said. “But relying on luck isn’t what we like to do.”

Julian Hernandez, a Hillside seventh grader, said he feels safer knowing that classmates infected with the virus will be prevented from spreading it to others.

“One of my friends — he got it a couple months ago while we was in school,” Julian recalled. “[He] and his brother had to go back home. … They were OK. They only had mild symptoms.”

Brandon Muñoz, who’s in the fifth grade, said he’s glad to get tested because he’s too young for the vaccine — and he really doesn’t want to go back to Zoom school.

“Because I wanna really meet more people and friends and just not stay on the computer for too long,” Brandon explained.

Suchinski, the superintendent, said Hillside also improved ventilation throughout the building, installing a new HVAC system and windows with screens in the cafeteria to bring more fresh air in the building.

Regular testing is an added layer of protection, though not the only thing Hillside is relying on: About 90% of Hillside staff are vaccinated, Suchinski said, and students and staffers also wear masks.

Setting up a regular mass-testing program inside a K-12 school takes a good amount of coordination, which Suchinski can vouch for.

Last school year, Hillside school administrators facilitated the saliva sample collection without outside help. This year, the school tapped funding earmarked for K-12 coronavirus testing to hire covid testers — who coordinate the collecting, transporting and processing of samples, and reporting results.

A couple of Hillside administrators help oversee the process on Mondays, and also facilitate testing for staff members, plus more frequent testing for a limited group of students: Athletes and children in band and extracurriculars test twice a week because they face greater risks of exposure to the virus from these activities.

Compared with a year ago, covid testing is now both more affordable and much less invasive, said Mara Aspinall, who studies biomedical testing at Arizona State University. There’s also more help to cover costs.

“The Biden administration has allocated $11 billion to different programs for testing,” Aspinall said. “There should be no school — public, private or charter — that can’t access that money for testing.”

Creating a mass testing program from scratch is a big lift. But more than half of all states have announced programs to help schools access the money and handle the logistics.

If every school tested every student once a week, the roughly $11 billion earmarked for testing would likely run out in a couple of months. (This assumes $20 to buy and process each test.) Put another way, if a quarter of all U.S. schools tested students weekly, the funds could last the rest of the school year, Aspinall said.

In its guidance to K-12 schools, updated Aug. 5, the Centers for Disease Control and Prevention does not make a firm recommendation for this surveillance testing.

Instead, the CDC advises schools that choose to offer testing to work with public health officials to determine a suitable approach, given rates of community transmission and other factors.

The agency previously recommended screening at least once a week in all areas experiencing moderate to high levels of community transmission. As of Sept. 21, that included 95% of U.S. counties.

For school leaders looking to explore options, Aspinall suggests a resource she helped write, which is cited within the CDC guidance to schools: the Rockefeller Foundation’s National Testing Action Plan.

This spring — when Hillside was operating at about half capacity and before the more contagious delta variant took over — the school identified 13 positive cases among students and staffers via its weekly testing program. The overall positivity rate of about half a percent made some wonder if all that testing was necessary.

But Suchinski said that by identifying the 13 positive cases, the school perhaps avoided more than a dozen potential outbreaks. Some of the positive cases were among people who weren’t showing symptoms but still could’ve spread the virus.

A couple of weeks into the new school year at Hillside, operating at full capacity, Suchinski said the excitement is palpable. Nowadays he’s balancing feelings of optimism with caution.

“It is great to hear kids laughing. It’s great to see kids on playgrounds,” Suchinski said.

“At the same time,” he added, “we know that we’re still fighting against the delta variant and we have to keep our guard up.”

This story is from a partnership that includes Illinois Public Media, Side Effects Public Media, NPR, and KHN.