The updated version of this document was released in November 2020 to address new scientific research results that have been published since the original document was released in June 2020 and to improve clarity in several instances. The updated version of this document also takes into account how the context has changed since the original document was published. The original document was written at the beginning of the summer, when many schools’ summer breaks had just begun. By November, the normal school year was well underway, with cooler winter weather and upcoming winter school holidays. The updated version of this document discusses both. No updates were made to the document structure, nor was wordsmithing undertaken except where deemed necessary to enhance clarity.
This updated November 2020 version supersedes the original June 2020 document.
Executive Summary, page 6: This section was updated to reflect the current context and state of knowledge in November 2020.
Introduction, page 16: A callout box was added to point readers toward guidance regarding how to adjust school reopening procedures based on the local level of community spread.
Understanding COVID-19, pages 21-23: Information regarding COVID-19 susceptibility, outcomes, symptoms, transmission, and infectivity that came from specific individual research studies was removed and replaced with information that reflects results from the much larger body of research that existed in November 2020 compared to June 2020. Accordingly, several research and review articles were added to the corresponding reference sections of the document.
Understanding COVID-19: When can someone transmit COVID-19?, page 22: The outdated WHO guidance that stated that two consecutive negative laboratory test results, taken at least 24 hours apart, can be used to determine the end of the COVID-19 infectious period was removed and replaced with the current WHO guidance regarding the end of the infectious period.
Healthy Classrooms: Wear masks, pages 25-26: This section was updated to include more forceful wording on mandatory mask wearing at all times by all individuals present in schools. The suggestion that face shields for teachers may be considered in some circumstances was removed.
Healthy Classrooms: Maximize physical distancing to protect individuals, page 28: This section was updated to indicate that while six feet of distancing is a good goal and should remain for adult to adult interactions, it should not be used as a hard cutoff and that three feet of distancing between children is acceptable for normal classroom activities.
Healthy Classrooms: Limit sharing of objects, page 30: This section replaces the original section called “Disinfect objects between users”. The new section includes much of the same information, but emphasizes handwashing, rather than disinfecting individual touched objects, as the most important risk reduction strategy when objects are being shared.
Healthy Buildings section introduction, page 31: The introduction to the “Healthy Buildings” section was updated to describe how ventilation, filtration, and supplemental air cleaning can work together to achieve target ventilation rates in school classrooms. The updated section also links to three additional resources on measuring ventilation rates and selecting portable air cleaners for classrooms that did not exist at the time the initial report was released in June, 2020.
Healthy Buildings: Increase outdoor air ventilation, pages 32-33: This section was updated slightly to emphasize increasing outdoor air ventilation rather than minimizing recirculation of air in classrooms. The decision tree diagram of general ventilation operation guidance for COVID-19 was also removed, as there are clearer and more detailed explanations of the same information both in the text of this document and in the first linked resource on page 31.
Healthy Buildings: Verify ventilation and filtration performance, page 35: Thissection was updated to point readers to a detailed resource on using CO 2 measurements to estimate outdoor air ventilation.
Healthy Buildings: Consider advanced air quality techniques, page 36: A note was added to this section to indicate that ventilation and filtration should be the prioritized healthy building risk reduction strategies in schools, as opposed to adjusting humidity.
Healthy Buildings: Use plexiglass as physical barrier, page 38: This section was updated to indicate that schools should be careful to evaluate air mixing when installing plexiglass barriers to make sure that they do not disrupt ventilation and air mixing.
Healthy Policies: Establish and reinforce a culture of health, safety, and shared responsibility, pages 40-41: This section was updated to explain how a culture of health, safety, and shared responsibility extends to choices that members of the school community make while they are not at school, including on weekends, evenings, and during school holidays, and to provide guidance on how to reduce risk during these times away from school.
Healthy Policies: Promote viral testing, page 43: Information on antibody testing was removed from this section, as testing to identify actively infectious people should be prioritized in schools.
Healthy Policies: Establish plans for when there is a case, page 43: CDC guidance for what to do when a case occurs was removed from this section; the document instead refers readers to CDC resources for the most up-to-date guidance.
Healthy Schedules: Make lunchtime safer, page 47: Information was added to this section to explain that engineering controls should be enhanced when students remove their masks to eat and drink at lunchtime.
Healthy Schedules: Modify attendance, page 51: Additional information regarding some problems with hybrid learning models, as well as when they may be useful, was added to this section.
Healthy Activities: Reimagine music and theater classes, pages 52-53: Some information was added to this section to encourage the use of enhanced risk reduction strategies for indoor music activities.
Healthy Activities: Continue sports with enhanced controls, pages 53-54: This section was updated to more strongly recommend mask wearing during all sports.
References: Citations for resources that informed the updates in this version were added.
