An increasing number of school districts are turning to testing to keep more children in the classroom and avoid disrupting the work lives of their parents. The resource-intensive approach — sometimes known as “test to stay” or modified quarantine — allows students who have been exposed to the virus to stay in school as long as they take frequent Covid tests, which are typically provided by the school, and adhere to other precautions.

Experts agree that children who are infected with the virus should isolate at home, but the question of what to do about their classmates poses a dilemma.

Allowing children who have been exposed to the virus to remain in school does pose a potential transmission risk, and the Centers for Disease Control and Prevention says that it “does not have enough evidence” to support the approach. Instead, it recommends that close contacts who have not been fully vaccinated quarantine for as long as 14 days. (Vaccinated close contacts can remain in the classroom as long as they are asymptomatic and wear a mask, according to the agency’s school guidance.)