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K-12 Schools should be last to close & First to Open


Executive Summary

As communities plan safe delivery of in-person instruction in K-12 schools, it is essential to decide when and under what conditions to help protect students, teachers, and staff and slow the spread of SARS-CoV-2, the virus that causes COVID-19. It is critical for schools to open as safely and as soon as possible, and remain open, to achieve the benefits of in-person learning and key support services. To enable schools to open safely and remain open, it is important to adopt and consistently implement actions to slow the spread of SARS-CoV-2 both in schools and in the community. This means that all community members, students, families, teachers, and school staff should take actions to protect themselves and others where they live, work, learn, and play. In short, success in preventing the introduction and subsequent transmission of SARS-CoV-2 in schools is connected to and facilitated by preventing transmission in the broader community.

This operational strategy presents recommendations based on the best-available evidence at the time of release. As science and data on COVID-19 continue to evolve, guidance and recommendations will be updated to reflect new evidence. This document is intended to complement CDC’s guidance, tools, and resources for K-12 schools, including guidance on operating schools during COVID-19 and overview of testing for SARS-CoV-2 (COVID-19). This document is intended to complement the U.S. Department of Education’s Handbook on Strategies for Safely Reopening Elementary and Secondary Schoolspdf iconexternal icon. It reflects evidence on COVID-19 among children and adolescents and what is known about SARS-CoV-2 transmission in schools, summarized in CDC’s Science Brief on Transmission of SARS-CoV-2 in K-12 Schools. This operational strategy presents a pathway to reopen schools and help them remain open through consistent use of mitigation strategies, especially universal and correct use of masks and physical distancing.

Evidence suggests that many K-12 schools that have strictly implemented mitigation strategies have been able to safely open for in-person instruction and remain open.1 This document provides an operational strategy to support K-12 schools in opening for in-person instruction and remaining open through an integrated package of mitigation components. These essential elements include:

  1. Consistent implementation of layered mitigation strategies to reduce transmission of SARS-CoV-2 in schools
  2. Indicators of community transmission to reflect level of community risk
  3. Phased mitigation and learning modes based on levels of community transmission

The following public health efforts provide additional layers of COVID-19 prevention in schools:

  • Testing to identify individuals with SARS-CoV-2 infection to limit transmission and outbreaks
  • Vaccination for teachers and school staff, and in communities, as soon as supply allows

Health Equity Considerations

The absence of in-person educational options may disadvantage children from low-resourced communities, which may include large representation of racial and ethnic minority groups, English learners, and students with disabilities. Plans for safe delivery of in-person instruction in K-12 schools must consider efforts to promote fair access to healthy educational environments for students and staff. Thus, essential elements of school reopening plans should take into account the communities and groups that have been disproportionately affected by COVID-19 infections and severe outcomes. Schools play a critical role in promoting equity in education and health for groups disproportionately affected by COVID-19.

Essential Elements of Safe K-12 School In-person Instruction

  1. Mitigation strategies to reduce transmission of SARS-CoV-2 in schools

Regardless of the level of community transmission, all schools should use and layer mitigation strategies. Five key mitigation strategies are essential to safe delivery of in-person instruction and help to mitigate COVID-19 transmission in schools:

Schools providing in-person instruction should prioritize two mitigation strategies:

  1. Universal and correct use of masks should be required, at all levels of community transmission. Require consistent and correct use of face masks, by all students, teachers, and staff to prevent SARS-CoV-2 transmission through respiratory droplets.
  2. Physical distancing (at least 6 feet) should be maximized to the greatest extent possible. To ensure physical distancing, schools should establish policies and implement structural interventions to promote physical distance of at least 6 feet between people. Cohorting or podding is recommended to minimize exposure across the school environment.

All mitigation strategies provide some level of protection, and layered strategies implemented concurrently provide the greatest level of protection. CDC’s K-12 Schools COVID-19 Mitigation Toolkitpdf icon includes resources, tools, and checklists to help school administrators and school officials prepare schools for in-person instruction. These tools and resources include aspects for addressing health equity considerations such as class sizes, internet connectivity, access to public transportation, and other topics.

  1. Indicators of community transmission

School administrators, working with local public health officials, should assess the level of risk in the community since the risk of introduction of a case in the school setting is dependent on the level of community transmission. CDC recommends the use of two measures of community burden to determine the level of risk of transmission: total number of new cases per 100,000 persons in the past 7 days; and percentage of nucleic acid amplification test (NAATs) results that are positive during the last 7 days. The two measures of community burden should be used to assess the incidence and spread of SARS-CoV-2 in the surrounding community (e.g., county). The transmission level for any given location will change over time and should be reassessed weekly for situational awareness and to continuously inform planning.

While risk of exposure to SARS-CoV-2 in a school may be lower when indicators of community spread are lower, this risk is also dependent upon the implementation of school and community mitigation strategies. If community transmission is low but school and community mitigation strategies are not implemented or inconsistently implemented, then the risk of exposure and subsequent transmission of SARS-CoV-2 in a school will increase. Alternately, if community transmission is high, but school and community mitigation strategies are implemented and strictly followed as recommended, then the risk of transmission of SARS-CoV-2 in a school will decrease.

  1. Phased mitigation, learning modes, and testing

At any level of community transmission, all schools have options to provide in-person instruction (either full or hybrid), through strict adherence to mitigation strategies1. Recommended learning modes vary to minimize risk of SARS-CoV-2 transmission in school by emphasizing layered mitigation, including school policies requiring universal and correct mask use. The recommended learning modes (in-person, hybrid, virtual) depend on the level of community transmission and strict adherence to mitigation.

This document presents an operational plan for schools that emphasizes mitigation at all levels of community transmission.

  • K–12 schools should be the last settings to close after all other mitigation measures in the community have been employed, and the first to reopen when they can do so safely. Schools should be prioritized for reopening and remaining open for in-person instruction over nonessential businesses and activities.
  • In-person instruction should be prioritized over extracurricular activities including sports and school events, to minimize risk of transmission in schools and protect in-person learning.
  • Lower incidence of COVID-19 among younger children compared to teenagers2 suggests that younger students (for example, elementary school students) are likely to have less risk of in-school transmission due to in-person learning than older students (middle school and high school).
  • Families of students who are at increased risk of severe illness (including those with special healthcare needs) or who live with people at increased risk should be given the option of virtual instruction regardless of the mode of learning offered.
  • Schools are encouraged to use cohorting or podding of students, especially in moderate (yellow), substantial (orange), and high (red) levels, to facilitate testing and contact tracing, and to minimize transmission across pods.
  • Schools that serve populations at risk for learning loss during virtual instruction should be prioritized for reopening and be provided the needed resources to implement mitigation.
  • When implementing phased mitigation in hybrid learning modes, schools should consider prioritizing in-person instruction for students with disabilities who may require special education and related services directly provided in school environments, as well as other students who may benefit from receiving essential instruction in a school setting.

Decisions should be guided by information on school-specific factors such as mitigation strategies implemented, local needs, stakeholder input, the number of cases among students, teachers, and staff, and school experience with safely reopening. A decision to remain open should involve considerations for further strengthening mitigation strategies and continuing to monitor case incidence and test positivity to reassess decisions.

Despite careful planning and consistent implementation of mitigation, some situations may occur that lead school officials to consider temporarily closing schools or parts of a school (such as a class or grade level) to in-person instruction. These decisions should be made based on careful considerations of a variety of factors and with the emphasis on ensuring the health and wellness of students, their families, and teachers and staff. Such situations may include classrooms or schools experiencing an active outbreak and schools in areas experiencing rapid or persistent rises in case incidence or severe burden on health care capacity.

Multiple SARS-CoV-2 variants are circulating globally. Some variants seem to spread more easily and quickly than other variants, which may lead to more cases of COVID-19. Rigorous implementation of and adherence to mitigation strategies is essential to control the spread of variants of SARS-CoV-2. As more information becomes available, it is possible that due to increased levels of community transmission resulting from a variant of SARS-CoV-2, mitigation strategies and school guidance may need to be updated to account for new evidence on risk of transmission and effectiveness of mitigation.

Additional COVID-19 Prevention in Schools


When schools implement testing combined with key mitigation strategies, they can detect new cases to prevent outbreaks, reduce the risk of further transmission, and protect students, teachers, and staff from COVID-19.

Diagnostic Testing

At all levels of community transmission, schools should offer referrals to diagnostic testing to any student, teacher, or staff member who exhibits symptoms of COVID-19 at school. Schools should advise teachers, staff, and students to stay home if they are sick or if they have been exposed to SARS-CoV-2 and refer these individuals for testing. They should also refer for testing asymptomatic individuals who were exposed to someone with a confirmed or suspected case of COVID-19. In some schools, school-based healthcare professionals (e.g., school nurses) may perform SARS-CoV-2 diagnostic testing (including rapid, point-of-care testing, and antigen testing) if they are trained in specimen collection and obtain a Clinical Laboratory Improvement Amendments (CLIA) certificate of waiverexternal icon. It is important that school-based healthcare professionals have access to, and training on, the proper use of personal protective equipment (PPE). If a COVID-19 diagnosis is confirmed, schools can assist public health officials in determining which close contacts could be tested and either isolated or quarantined. Individuals should isolate or quarantine at home, not in school settings, and should stay home until it is safe for them to be around others.

Screening Testing

Some schools may also elect to use screening testing as a strategy to identify cases and prevent secondary transmission. Screening testing can be used as an additional layer of mitigation to complement mitigation strategies in schools. Screening testing is intended to identify infected individuals without symptoms (or prior to development of symptoms) who may be contagious so that measures can be taken to prevent further transmission. For schools that implement expanded screening testing, screening testing should be offered at moderate (yellow), substantial (orange), and high (red) levels of community transmission, to students, teachers, and staff and at low (blue) levels to teachers and staff who have no symptoms and no known exposures. Additional considerations in implementing screening testing:

  • When determining which individuals should be selected for screening testing, schools and public health officials may consider prioritizing teachers and staff over students given the higher risk of severe disease outcomes among adults. In selecting among students, schools and public health officials may choose to prioritize high school students, then middle school students, then elementary school students, where applicable.
  • Public health officials and school administrators may consider placing a higher priority for access to testing in schools that serve populations experiencing a disproportionate burden of COVID-19 cases or severe disease. These may include schools in communities with moderate or large proportions of racial and ethnic groups that have experienced disproportionately high rates of COVID-19 cases relative to population size, and schools in geographic areas with limited access to testing due to distance or lack of availability of testing.
  • Every COVID-19 testing site is required to report to state or local health officials all testing performed. Schools that use testing must apply for and receive a Clinical Laboratory Improvement Amendments (CLIA) external iconcertificate of waiver. Schools must report test results to state or local public health departments as mandated by the Coronavirus Aid, Relief, and Economic Security (CARES) Act.
  • Testing should be offered on a voluntary basis. Consent from a parent or legal guardian (for minor students) or from the individual (for adults, including adult students and teachers and staff) is required for school-based testing.

Vaccination for teachers and staff, and in communities as soon as supply allows

Teachers and school staff hold jobs critical to the continued functioning of society and are at potential occupational risk of exposure to SARS-CoV-2. State, territorial, local and tribal (STLT) officials should consider giving high priority to teachers in early phases of vaccine distribution. The Advisory Committee on Immunization Practices (ACIP) recommends that frontline essential workers, including those who work in the education sector (teachers and school staff), be prioritized for vaccine allocation in phase 1b, following health care personnel and residents of long-term care facilities (phase 1a). Vaccinating teachers and school staff can be considered one layer of mitigation and protection for staff and students. Strategies to minimize barriers to accessing vaccination for teachers and other frontline essential workers, such as vaccine clinics at or close to the place of work, are optimal. Access to vaccination should not be considered a condition for reopening schools for in-person instruction. Even after teachers and staff are vaccinated, schools need to continue mitigation measures for the foreseeable future, including requiring masks in schools and physical distancing.