Summarizing CDC Guidance to Support COVID-19 Contact Tracing in K-12 Schools

October 05, 2021

As schools work to stay open for in-person learning, it is essential to understand key recommendations related to COVID-19 prevention in K-12 schools. CDC recommends that health department staff work closely with K-12 schools to effectively prevent and respond to COVID-19 infections. Health department staff may look to school officials to understand the unique context of each school setting, while school officials may look to health department staff to better understand federal, state, and local guidance. This brief compiles CDC guidance for COVID-19 prevention strategies in K-12 schools and should supplement state or territorial and local policies. Schools and health departments should layer the COVID-19 prevention strategies listed below for maximum impact.

CDC Resource

Key CDC Recommendations

Vaccinate People Ages 12+

CDC recommends that everyone older than 12 years of age receive a COVID-19 vaccine. Vaccination is the leading public health prevention strategy to end the COVID-19 pandemic. COVID-19 vaccines are safe, effective, and reduce the risk of severe illness from COVID-19. Currently, COVID-19 vaccines are only available to those over 12 years of age. A person is considered fully vaccinated two weeks after they receive a second dose of a two-dose series (such as Pfizer or Moderna vaccines) or two weeks after a single-dose vaccine (such as Johnson & Johnson’s Janssen vaccine).

Wear Protective Face Masks

CDC recommends that all students, staff, teachers and visitors above the age of two wear face masks indoors, regardless of vaccination status. Outdoors, individuals may consider wearing a mask in crowded outdoor settings, especially if they are in an area with a high number of COVID-19 cases. On school buses, a CDC order mandates that both passengers and drivers must wear a face mask throughout the trip, regardless of vaccination status.

Avoid Close Contact

Generally, persons with COVID-19 are considered to be in close contact with another individual if they are within six feet of that person, for a total of 15 minutes or more over a 24-hour period, regardless of whether either person was wearing a mask. CDC provides additional guidance for some settings.

Because of the unique factors of indoor K-12 classrooms and structured outdoor school settings, students with COVID-19 are not considered to be in close contact with another student if they are wearing well-fitted masks and are between three and six feet away. This only applies to students, and NOT to teachers, staff, or other adults who are in the classroom at the same time.

Some schools may develop groups of students and teachers that stay together (i.e., cohorting) throughout the day to limit the number of individuals interacting. Cohorting should not be based on vaccination status, academic achievement, race, or in any other inequitable manners described in the U.S. Department of Education COVID-19 Handbook.

Test Appropriately and Regularly

Regular COVID-19 testing for teachers, staff, and students, combined with vaccination, may help protect those who are not vaccinated or are otherwise at risk for severe illness. People who have been in close contact with someone with COVID-19 should get a diagnostic test, except for someone who has (1) been diagnosed with COVID-19 within the previous 3 months, (2) has recovered, and (3) has not had COVID- 19 symptoms since recovering.

Someone who has been fully vaccinated and shows no symptoms of COVID-19 should be tested three to five days after exposure to someone with suspected or confirmed COVID-19. They should also wear a mask in public indoor settings for 14 days or until they receive a negative test result. Here is an additional CDC resource on COVID-19 testing:

Jurisdictions Set Up School-Based Vaccine Clinics

Schools and local health departments in Maricopa County, Pima County, and others, have partnered to set up school- based vaccine clinics to vaccinate staff and students 12 years and older.

Quarantine as Necessary

In general, people who have been in close contact with someone with suspected or confirmed COVID-19 should quarantine for 14 days after their last exposure to COVID-19. Local public health authorities may provide options for an individual to shorten their quarantine period after 10 days, or after seven days if the person receives a negative test result.

A person who is fully vaccinated and shows no symptoms of COVID-19 may not need to quarantine. This person should get tested three to five days after their last exposure and wear a mask indoors in public for 14 days, or until they receive a negative test result. Read additional CDC guidance on quarantine periods.


Health departments and schools should work together to implement COVID-19 prevention measures that make sense for the unique school setting. To be most effective, the prevention measures listed above should be implemented with a layered approach and should supplement state and local policies and guidance.

States Successfully Use Options to Test-Out of Quarantine

Illinois, for example, has implemented a “test-to-stay” option in which close contacts who continue to test negative 1, 3, 5, and 7 after exposure may remain in the classroom. This policy does require that other prevention measures be in place, including universal indoor masking. California, Kansas, and Massachusetts are among the other states that offer options to test out of quarantine.