CDC Issues K-12 School Reopening Guidance

Under the “best-available evidence at the time of release (February 12, 2021)”, the Centers for Disease Control and Prevention (CDC) issued an operational strategy that provides recommendations for in-person instruction in K-12 schools. This summary document is intended to complement the 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).

Evidence continues to show that K-12 schools that have strictly implemented mitigation strategies have remained safely open or have safely reopened for in-person instruction[1]. The newly released operational strategy from the CDC is a tool to support K-12 schools in opening or remaining open for in-person instruction and to stay safely operational through an integrated package of mitigation components identified as the “Essential Elements of Safe K-12 School In-person Instruction” including:

  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.

Public health efforts providing an additional layer of COVID-19 prevention include testing to identify individuals with SARS-CoV-2 infection and vaccination for teachers and school staff, and in communities.

Consistent Implementation of Layered Mitigation Strategies to Reduce Transmission of SARS-CoV-2 in Schools

The CDC recommends K-12 schools implement four mitigation strategies:

  1. Universal and correct use of masks;
  2. Physical distancing;
  3. Cleaning and maintaining healthy facilities including improving ventilation to increase the delivery of clean air to the fullest extent possible;
  4. Contact tracing in combination with isolation and quarantine, in collaboration with the health department.

While each strategy provides some level of protection, layering all five concurrently provides the greatest level of protection. On March 19, 2021, the CDC issued updated guidance on its’ operational strategy for K-12 schools, specifically relating to the recommended physical distance between students in classrooms. In contrast to the previously recommended distance of at least 6’, the updated CDC guidance recommends that, with a universal masking policy in place and enforced, students at the elementary school level should maintain a distance of at least 3’ in classroom settings. This recommendation is applicable whether community transmission is low, moderate, substantial, or high. In middle or high school environments where cohorting of students is not possible, students should still maintain a distance of at least 6’. The 6’ recommendation remains in place for older students because COVID-19 transmission dynamics are different in older students and they are more likely to be exposed to SARS-COV-2 and spread COVID-19 than younger children. In a school setting, the CDC continues to recommend at least 6’ of physical distance between adults and between adults and students, in common areas, when masks cannot be worn (eating), during activities when increased exhalation occurs (singing, shouting, band practice, sports, or exercise) and in community settings outside the classroom.

Indicators of Community Transmission

The CDC says K-12 school administrators should work with local public officials to 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. The two measures of community burden to determine the level of risk of transmission include: 1) the total number of new cases per 100,000 persons in the past 7 days and 2) percentage of nucleic acid amplification test (NAATs) results that are positive during the last 7 days. 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 the indicators of community spread may reduce the risk of exposure to SARS-CoV-2 in a school, the CDC stresses the importance 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.

Phased Mitigation, Learning Modes, and Testing

The CDC states, at any level of community transmission, all schools have options to provide in-person instruction (either full or hybrid), through strict adherence to mitigation strategies. The 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.

The operational strategy document provides a 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 teenagers suggests that younger students (ex. 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 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.

The CDC says, 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 to in-person instruction. 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. In addition, the CDC recognizes multiple SARS-CoV-2 variants that are circulating globally and some variants seem to spread more easily and quickly than other variants, which may lead to more cases of COVID-19. As more information becomes available, the CDC says 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.

Overall, the CDC states that the strategy presents a pathway to reopen schools and help them remain open through consistent use of mitigation strategies through a layered approach and all members of a school’s community, its students, families, teachers and 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.

Ventilation and School Re-Opening

As described above and recommended by the CDC, ventilation is a principal component of maintaining a healthy environment and is an important COVID-19 risk reduction strategy for schools. The American Industrial Hygiene Association (AIHA) and eight other leading scientific organizations have endorsed the Joint Consensus Statement on Addressing the Aerosol Transmission of SARS CoV-2 and Recommendations for Preventing Occupational Exposures that summarizes the current knowledge of occupational health professionals and scientists surrounding airborne SARS-CoV-2 transmission and outlines their recommendations calling for regulation, research, and funding towards the prevention of airborne transmission.

RHP professionals are considered trusted advisors and experts by school administrators when planning and preparing for a harmonious reopening process to achieve in-person services and provide a hazard assessment for identifying risks and addressing hazards to ease fears, answer parent/community/student fears, concerns and frustrations.

Furthermore, RHP professionals partner with schools, childcare centers, daycares, universities, and institutions for higher education to analyze infectious disease plans for best practices, protocols, and guidance for reopening actions as well as conduct detailed verification and validation assessments of your buildings ventilation system. Through engineering controls, administrative controls (e.g., surface cleaning), masking, hygiene, and social distancing requirements, RHP works with building maintenance, engineers and administrators to assess and validate procedures which will lead to safer, trusted and practical procedures to expedite opening and in person learning.

For more information on RHP’s school reopening and ventilation services and contact information, please visit