Skip to Main Content
Skip Nav Destination
Students wearing masks in school.

Test-to-stay practices can keep more children in schools, reduce loss of in-person learning: CDC

December 17, 2021

Editor’s note: For the latest news on COVID-19, visit 

Two studies released Friday by the Centers for Disease Control and Prevention (CDC) demonstrated that test-to-stay (TTS) practices used in two public school systems resulted in more students being able to remain in the classroom following school-related exposures to COVID-19.  

The reports analyzed TTS initiatives permitted at dozens of schools in Los Angeles County and Lake County, Ill., during the fall of 2021. The Los Angeles County report can be read here, while the Lake County report is available here 

Between Sept. 20 and Oct. 31, 432 of the 2,067 schools in Los Angeles County adopted a TTS protocol, which allowed unvaccinated students exposed in school to a person infected with COVID-19 to remain in school while under quarantine and awaiting test results, if both the infected person and the exposed person had been wearing masks correctly and consistently throughout the exposure. To stay in school, the exposed student must remain asymptomatic, wear a mask while at school and undergo twice weekly COVID-19 testing. During the TTS period, students also must agree to quarantine at home while not in school and cannot participate in extracurricular activities or before- or after-school care during the quarantine period. 

Participating schools did not experience increases in COVID-19 incidence among students after TTS implementation, and in 20 identified outbreaks in TTS schools no transmission from a student with a secondary case was identified, according to the CDC report. 

In the Lake County study, 90 schools representing 31 school districts implemented TTS from Aug. 9 through Oct. 29, with requirements similar to those in the Los Angeles TTS program. During that period, 258 COVID-19 cases were reported, which resulted in 1,035 students and staff members enrolling in TTS. The secondary attack risk, or the number of close contacts who received a positive COVID-19 test result within 14 days after exposure, was 1.5%, or just 16 cases.  

All 16 cases involved students, and none of the 16 appeared to transmit COVID-19 to other school-based contacts. However, nine tertiary cases were identified among household contacts of the 16 secondary cases, and four of the nine were fully vaccinated individuals.  

“These studies demonstrate that test-to-stay works to keep unvaccinated children in schools safely,” CDC Director Rochelle P. Walensky, M.D., M.P.H., said during a Friday press conference. “In order for test-to-stay to be implemented safely and correctly, some key prevention measures need to be included. In both studies, masks were worn consistently and correctly. Close contacts of a positive case were monitored for symptoms and stayed home if they became ill.  

“The CDC is updating our materials to help schools and parents know how to best implement this promising and now proven practice, along with our multilayer prevention strategies that will keep our children in the classroom,” said Dr. Walensky. 

Assuming a maximum of eight missed school days for every 10-day quarantine period, up to 8,152 in-person learning days were saved among TTS participants in Lake County, according to the report.  

Within the 1,635 non-TTS school districts in Los Angeles County, 4,322 COVID-19 cases were reported among 967,188 enrolled students. Non-TTS districts lost an estimated 92,455 in-person school days during the study period. Within the 432 TTS schools, 812 cases of COVID-19 were reported among 324,879 enrolled students, and no in-person school days were lost among quarantined students participating in TTS. 

The reports note a TTS plan requires staffing resources and systems to monitor eligibility for and compliance to TTS that might not be available in schools in under-resourced communities, including most Los Angeles County non-TTS schools. In Lake County, only schools with sufficient resources offered TTS. 

The findings in the reports were subject to some limitations, which include monitoring systems not being established to assess compliance with TTS requirements or designed to evaluate school transmission before and after TTS adoption. In Los Angeles County, non-TTS schools were disproportionately located in the most under-resourced neighborhoods, where population case rates tend to be the highest, which may explain the difference in student case rates in TTS and non-TTS schools.  

While TTS can lead to more students being allowed to remain in schools, doctors continue to stress the importance of getting vaccinated, wearing masks in indoor settings, physically distancing and proper ventilation within school buildings as some of the many tools used to help slow the spread of the virus.  

According to Dr. Walensky, more than 20 million children ages five to 11 have been vaccinated in the United States, including five million who are under the age of 11. The CDC recommends everyone 5 years old and older get a COVID-19 vaccine to protect against the virus, while adolescents 16 years and older can receive a booster shot at least six months after a primary series.  

“The most common reported side-effects included pain at the injection site, fever, tiredness, headaches and muscle aches, which we know are normal and are all signs that the body is building immunity to the virus,” Dr. Walensky said. “This further adds to the strong evidence of the safety of these vaccines for children and should be an encouraging reason for those who are waiting for more data to now feel confident in making the decision to get your child vaccinated.”  

To find a vaccine location near you, visit 


Close Modal

or Create an Account

Close Modal
Close Modal