Students who have been exposed to the coronavirus can safely continue in-person learning if they are regularly tested for the virus at school, avoiding disruptive at-home quarantines, the U.S. Centers for Disease Control and Prevention said Friday.

The CDC released two studies that show the effectiveness of what’s known as “test-to-stay.” School districts across the country have tried this strategy, though it is not widely used.

“These studies demonstrate that test-to-stay works to keep unvaccinated children in school safely,” CDC Director Rochelle Walensky told reporters Friday. She called it “a promising and now proven practice.”

Typically, students who are deemed close contacts of someone who tests positive for the virus are sent home to quarantine, to make sure that people who may be carrying the virus, even without symptoms, do not infect others. But under a test-to-stay policy, students who are asymptomatic and test negative for the virus after an exposure can continue in-person learning.

Many schools in Maine are already implementing regular testing through a pooled PCR testing program that allows large groups of students and staff to be tested on a weekly basis. Those who participate in the program can avoid school quarantines as long as they continue to test negative and remain asymptomatic.

Lewiston Superintendent Jake Langlais said the new “test to stay” findings from the CDC could open the door to more opportunities for students to stay in school after a COVID exposure beyond what is already available through the pooled testing program.

Langlais said he would wait to see what new guidance may come from the state or Maine Department of Education, but he is hopeful it would allow options for students who are exposed in an out-of-school setting such as church or club sports to present negative tests in order to return to school or for schools to administer tests after a COVID exposure to students who are not part of pooled testing.

“We don’t have any local rulings on this yet, but my read was if a student is exposed they could get a ‘test to stay’ and that could be (from an exposure) anywhere,” Langlais said.

A Maine Department of Education spokeswoman did not respond to messages left late Friday night about questions on how the CDC findings might impact the state. Some Maine superintendents said they hadn’t yet had a chance to review the CDC information, but regular pooled testing is already working well for them in mitigating quarantines.

“I am very, very happy we are signed up for it,” said Regional School Unit 23 Superintendent John Suttie in Old Orchard Beach. “It’s made a huge difference in our ability to keep kids in school five days per week and has kept the pressure off families to have to find child care when their kids have to quarantine.”

The CDC studied test-to-stay alternative programs in Lake County, Illinois, and Los Angeles County.

“Test-to-stay is an encouraging public health practice to help keep our children in school,” Walensky said.

Quarantines of students have been controversial because they interrupt learning as schools are laboring to make up for months of often substandard remote education. They also force many parents to scramble for child care at the last minute. With positive cases rising, the number of children in quarantine also has been climbing quickly.

Education Secretary Miguel Cardona welcomed the news, particularly in light of evidence of the harm caused by remote schooling. “Schools across the country must do everything possible to keep students safe and ensure that they are able to access high-quality, in-person instruction safely in their schools,” he said Friday.

But test-to-stay requires significant resources. There is a shortage of the rapid tests used by schools. And these programs require school personnel to administer the tests, something not every school district is able to muster.

Walensky said the CDC would update its materials to help schools and parents implement this approach. However, in the face of rising case counts and concerns that all districts cannot mount a test-to-stay program, the agency opted against updating its formal guidance to schools to recommend a switch to test-to-stay.

That guidance still recommends that unvaccinated students who come into close contact with a person who has the virus should quarantine for seven to 14 days after exposure.

The two new studies, published in the CDC’s Morbidity and Mortality Weekly Report, looked at how test-to-stay was implemented this fall.

In both cases, Walensky noted, students wore masks. Close contacts of the people who tested positive were monitored for symptoms and told to stay home if they became sick. Contacts who came back to school were regularly tested – at least twice over the seven days after exposure.

In Los Angeles County, about half off the 78 school districts, which include 21 percent of the county’s schools, used test-to-stay instead of quarantine this fall. In those schools, there were 20 outbreaks identified but transmission was no higher than before the program was adopted.

Students in county schools using quarantine, including the largest district, Los Angeles Unified, lost a total of more than 92,000 in-person school days, where students in test-to-stay programs lost none.

The test-to-stay program is just now being rolled out in Oregon but already is popular with districts, said Jim Green, executive director of the Oregon School Boards Association.

“We’ve had to quarantine kids for up to 14 days,” he said. “Given everything that’s gone on in the pandemic, is that what’s best for kids? Do you want kids out of school just because they’ve come in contact with someone with COVID? If we can do a rapid test and show they are negative and keep them in school, that’s our goal.”

Press Herald Staff Writer Rachel Ohm contributed to this report.