Practical Guide for Operationalizing CDC’s School Guidance

Updated December 3, 2021.

Effective August 1, 2021.

Table of contents
Summary of Recent Changes
  • Updated to recommend universal indoor masking for all students, staff, teachers, and visitors to K-12 schools, regardless of vaccination status and at all levels of community transmission.

  • Updated “Table: Criteria for Reduced Quarantine” to remove the community vaccination metric for shifting to use of reduced quarantine for typical classroom exposures.

  • Updated “Table: Criteria for Reduced Quarantine” to increase the threshold for high rates of school community COVID-19 vaccination from 70% to 80%.

  • Added new language emphasizing the importance of improving ventilation and air filtration in reducing the risk of COVID-19 transmission.

  • Clarified recommendations for quarantine determinations based on distance and masking in typical classroom and non-classroom settings in both the body of the guidance and in the updated  Who Needs to Quarantine tool.

Colorado is following CDC’s recommendations for schools. This guide is designed to help schools operationalize and clarify CDC’s recommendations.


Executive Summary

Colorado has made tremendous strides in decreasing transmission and deaths from COVID-19, including reaching more than a 70% vaccination rate among adults 18 and older statewide. In addition, Governor Polis ended the disaster emergency, signaling our transition as a state from crisis to recovery. Yet unvaccinated Coloradans remain vulnerable to new variants, especially the Delta variant, which is far more contagious than previous variants and may have more severe health outcomes for younger people. 

Because many students have yet to be vaccinated and students under 5 are not yet eligible, we must continue to remain vigilant, take important mitigation steps that can reduce transmission of COVID-19, and address outbreaks in a safe and thoughtful manner. Colorado Department of Public Health and Environment (CDPHE) will adopt and elaborate upon  CDC school guidance, which was released on July 9, 2021. This includes an updated August 4, 2021,  recommendation for universal indoor masking in schools regardless of vaccination status at all levels of community transmission. CDPHE is providing this practical guide for schools, parents, and students on how to operationalize CDC guidance in our education settings. 

This guide to operationalizing CDC guidance is aimed at disease control and minimizing the risk of exposure in education settings. But, we know students’ wellness extends well beyond just disease control. Schools, educators, parents, and students must balance all of the needs of our students in order to achieve wellness and create a productive learning environment. With this in mind, the state has let all statewide school-based health orders and mandates expire and instead has adopted a guidance model designed to empower local public health and local leaders to protect their communities using the mitigation strategies most appropriate to local conditions. The guidance provides practical tools to assess the risks of COVID-19 and minimize those risks. The guidance does not constitute statewide requirements, but instead outlines evidence-based best practices for local governments and schools to implement together to manage the next stage of the pandemic. 

The state continues to recommend a layered approach of best practices to COVID-19 prevention. This outline of best practices is described in detail in the Back to School Roadmap, including ventilation, maximization of outdoor activities, mask-wearing, testing, spacing, cohorting, symptom screening, cleaning and disinfecting, and handwashing. It also includes information for local public health agencies, schools, and parents about community transmission and layered precautions. 

This guidance strongly recommends local leaders and school leaders take a layered approach to prevention as described above. Communities with higher rates of transmission and low vaccination rates should continue to take heightened COVID-19 precautions. Local public health still has the authority to enforce local public health orders, which may include quarantine requirements. 

When schools have low vaccination rates (defined as a vaccination rate under 80% among staff and students age 12 and older) and their communities are experiencing high rates of community transmission (defined  as 35 cases per 100,000 people over seven days), the local public health agency should work with schools and school districts to institute higher precautionary measures, such as:

  • Universal masking (if not already implemented as recommended at all transmission levels).

  • Increased physical distancing. 

  • Serial COVID-19 testing and screening programs.

  • Contact tracing. 

  • Targeted quarantining.

  • Limiting high risk activities. 

In addition to communities facing higher risk factors, certain student groups may be at greater risk of COVID-19 due to the nature of their activities. Riskier activities include indoor sports, contact sports, and other activities involving forced exhalation such as band or orchestra. In these higher risk settings, local public health and school districts should consider precautionary measures to prevent the spread of COVID-19, such as universal masking, serial testing and screening programs, contact tracing, targeted quarantining, vaccine outreach, and educational efforts. During the spring 2021 semester, outbreaks of COVID-19 often originated with these groups of students and then spread to the larger school community, disrupting learning. 

Similar to adults, students with underlying health conditions such as obesity, diabetes, asthma, down syndrome, and heart disease are more likely to experience severe health impacts, hospitalization, and death from COVID-19. Students and staff with these underlying health conditions are strongly advised to get vaccinated. If they cannot get vaccinated, they should continue practicing a layered approach to prevent COVID-19. 

Regardless of transmission and vaccination rates, all education settings should create the safest environment possible for their students through tried-and -true disease prevention measures. These include promoting hand washing, ensuring good ventilation, encouraging activities outside, social distancing, and asking sick students to stay home following CDPHE’s Return to Learn tool. In addition, CDC and CDPHE recommend universal indoor masking for all teachers, staff, students, and visitors to K-12 schools, regardless of vaccination status. Universal masking is an especially critical strategy when a community is at higher risk of transmission, such as when vaccination rates are low and in schools where students are not yet eligible for vaccination. Schools should create an accepting environment for parents and students who choose to use masks even when they are not required. 

Not only is COVID-19 vaccination Colorado’s best defense against the pandemic, vaccination also prevents disruptions to in-person learning. Fully vaccinated staff and students never have to miss school due to quarantine. The COVID-19 vaccines have been highly successful at reducing transmission, infections, and deaths. As we look towards the fall, CDPHE looks forward to partnering with schools and districts to host vaccination clinics and increase our defense against this virus. Vaccines are essential for students and caretakers alike. Children’s risk of contracting COVID-19 is greatly reduced when they live in a household where all eligible individuals are fully vaccinated, even if the children are not yet eligible for vaccination. Any school or school district interested in hosting a vaccination clinic can complete the online Vaccination Event Request Form. Throughout the school year, CDPHE will monitor disease transmission, severity, and vaccine effectiveness trends as well as community feedback. We will update our guidance and disease control strategies as the COVID-19 landscape changes with a continued focus on the essential nature of in-person learning.

Both local and state public health have statutory, legal and regulatory authority to investigate and control disease transmission, including isolation of cases and quarantine of close contacts, closing public places and prohibiting gathering to control the spread of disease. Statutory citations include but are not limited to 25-1.5-102(1), 25-1-506(3)(b)(V), 25-1-122(2), 25-1.5-101(1)(a),(h),(k) and (l), C.R.S.. Regulatory authority includes, 6 CCR 1009-1, 6 CCR 1010-6 and 6 CCR 1010-7.


This guidance applies to all circumstances where a teacher or caregiver cares for multiple children outside the usual home of the children. These circumstances include, but are not limited to:

  • K-12 schools, both public and private.

  • Licensed child care settings.

  • Home-based family child care settings.

  • License-exempt child care programs such as single skill building and 72-hour camps.

  • Guest child care facilities at ski resorts and courthouses.

  • “Pods” and other home learning/homeschooling groups.

This guide also applies to extracurricular activities, including sports, where the participants are in grades P-12. Additional guidance for sports can be found on the Organized sports page. 

Special considerations for ECE

Child care and pre-K settings are different from K-12 settings in important ways. The particular facilities, curriculum, and modes of supervision in child care facilities require modifications to  guidance developed for K-12 settings. Please take note of special recommendations for pre-K and child care settings throughout this guidance. In the guidance and tools, the term “schools” includes K-12 schools and child care providers, including in-home providers.

Residential settings, including overnight camps and group homes, have different transmission characteristics and abilities to isolate and quarantine compared to K-12 schools and other child care settings. These settings should follow the outbreak guidance relevant to their particular circumstances. 


School outbreak-associated case: a case among students, teachers, or staff that meets the outbreak definition. Family members or others outside the school who get sick should not be classified as outbreak-associated.

Outbreak: Outbreaks are defined in Colorado’s COVID-19 case and outbreak definitions.

COVID-like symptoms: loss of taste or smell, fever (100.4°F or higher), chills, new or worsening cough, shortness of breath or difficulty breathing, headache, sore throat, muscle or body aches, congestion or runny nose, fatigue, nausea or vomiting, diarrhea. A person is assumed to be contagious two days before they start having symptoms and for 10 days after symptoms start. In children too young or unable to reliably report their symptoms, caregivers and teachers should monitor for symptoms and other age-appropriate signs of disease, including decreased appetite or activity. All symptomatic individuals should seek clinical evaluation, including testing, as soon as possible after symptoms develop.

Isolation: staying home from work, school, and activities when a person is sick or diagnosed with COVID-19. Isolation lasts for at least 10 days (specifically ten 24-hour periods) after the onset of symptoms — and for 24 hours after being fever-free without the aid of fever-reducing medication and if the person shows an improvement of symptoms. For people who have not had symptoms, isolation lasts 10 days from the day they had their first positive test. In rare instances (for example, if a person was very sick or has certain medical problems), isolation may last 20 days. Public health experts do not recommend repeat testing to decide when to end the period of isolation except in rare circumstances in consultation with a medical provider. Find information about how to isolate

Quarantine: staying home from work, school, and activities after a person was in close contact with someone with COVID-19. Find guidance on how to quarantine and how long quarantine lasts.  A person should not attend work, school, or out of school activities if they are under quarantine following an exposure in school. If a person develops symptoms of COVID-19 during their quarantine period, they should begin isolation.

Close contact: a person who was close enough to a person with COVID-19 or symptoms of COVID-19 to be at risk of becoming ill. 

Diagnostic COVID-19 test: a test that detects a current COVID-19 infection. These tests include PCR, rapid molecular, and antigen tests. Serology tests can check for evidence of past infection or vaccination, but cannot reliably tell if a person currently has COVID-19 so are not considered diagnostic tests. Testing types are explained further on the FDA's website.

Prioritizing in-person learning

We must support and prioritize uninterrupted, full-time, in-person learning in all communities. While we must remain vigilant, particularly when it comes to deadly COVID-19 variants, we recognize there are fewer cases of COVID-19 than earlier in the pandemic, and children under the age of 12 are less likely to experience severe disease, hospitalization, and death from COVID-19. We also know that vaccinations are our best defense against COVID-19. Therefore, Colorado will move from an individual case-based response strategy to a transmission mitigation strategy, where instead of quarantining students and staff after individual exposures, the risk of the whole school community, including the risk of interruptions to learning,  is considered. Because in-person learning is essential for communities and students to thrive, CDPHE is recommending reduced incidents of quarantine in schools and child care specifically. Reduced quarantine is not recommended in other settings at this time. 

Preventive measures

The state continues to recommend a layered approach of best practices to COVID-19 prevention. These best practices are described in detail in the Back to School Roadmap, and include ventilation, maximization of outdoor activities, sick leave policies, mask-wearing, testing, spacing, cohorting, symptom screening, cleaning and disinfecting, and handwashing. These policies will continue to be important for preventing transmission of all diseases in schools.

Mask wearing

CDC recommends universal indoor masking for all teachers, staff, students, and visitors to K-12 schools, regardless of vaccination status and at all transmission levels. CDPHE recommends local public health agencies and school districts implement universal mask requirements for all individuals entering K-12 schools in Colorado. This is especially important in settings where vaccination rates are low and where many students are not yet eligible for vaccination. Those who cannot medically tolerate a mask should work with their school administration to assess the need for a reasonable accommodation in accordance with the Americans with Disabilities Act (ADA). Additional information regarding reasonable accommodations can also be found in the State’s Civil Rights Guidance. Both state and local public health have the authority to issue public health orders requiring masks, and include within those orders any allowable exceptions to the mask requirement. For settings in which masks are required by the State, exceptions include temporary removal of a mask to participate in a life rite or religious service where such temporary removal is necessary for participation; there is no broader general exemption from wearing a mask for religious or personal belief in the state public health orders. In addition, even when not required by local public health or a school district, staff and students may choose to wear masks. Schools and school districts should ensure that every classroom is a welcome environment for students and staff who choose to protect themselves in this manner. 

Improving ventilation 

COVID-19 and other respiratory illnesses are spread through respiratory droplets that are produced when we breathe, talk, sneeze, or cough. Improving ventilation by increasing air exchanges and filtration assists with the dilution of contaminants that might be present, including respiratory droplets.  Schools can improve ventilation in a number of ways. 

Existing HVAC systems should be maintained in good working order, and should run for at least 30 minutes before and after the building is occupied. 

Schools without existing HVAC systems or inadequate systems can open windows during the school day to increase ventilation and air flow. 

Additionally HEPA filters can be added to an existing HVAC system and portable HEPA filters can be added to areas to filter out contaminants from the air. 

Outdoor activities are strongly encouraged, especially for higher risk activities and meal times. 

Additional resources on improving ventilation

Isolation of positive cases

Ensuring sick people stay home (and people diagnosed with COVID-19 follow isolation requirements) is critical to preventing the spread of COVID-19. Under state law, isolation of positive cases is required and must be enforced by local public health and school districts. 

Monitoring and communication

While fully vaccinated individuals are not required to quarantine if they are exposed to someone with COVID-19, all individuals who are exposed should monitor themselves for symptoms for 14 days and get tested if symptoms develop.

We continue to recommend alerting students, staff, and parents of known classroom exposures so all individuals are appropriately informed, will monitor closely for symptoms, and may choose to increase personal mitigation measures as necessary when living or working with vulnerable individuals (e.g. a high school student who volunteers in a nursing home or who lives with an immunosuppressed relative).  

Quarantine for routine classroom exposures

The state recommends counties, schools, and individuals that meet any of the below metrics shift to a transmission control strategy, with quarantine not required following routine classroom exposures. Large outbreaks or important circulating variants may necessitate more stringent disease control strategies at the discretion of the local public health agency (LPHA).

Table: Criteria for Reduced Quarantine 

County population protections

School community protections

Individual protections

Low community transmission

High rates of school community COVID-19 vaccination

  • ≥80% of staff and students 12 and older with at least one COVID-19 vaccination


High rates of weekly school screening testing

  • ≥70% of unvaccinated staff and students participating in weekly testing

Fully vaccinated (two weeks after last recommended vaccine dose)


Previously positive in the past 90 days


Participating in weekly screening testing


Both parties wearing a mask at the time of exposure*

Quarantine of close contacts does not need to be required by local public health authorities following routine classroom exposures if any of the above are met by the county, school, or individual considered a close contact (*and the ill individual for mask use).


Quarantine in counties with low vaccination and high case rates

Even in schools with low vaccination rates or in counties with high case rates, the state recommends multiple ways schools can avoid quarantine for lower risk, typical classroom exposures, at the discretion of the local public health authority. Schools must work with their local public health agency when cases of COVID-19 are identified to determine quarantine requirements. 

  • Vaccinated Individuals
    • Anyone who is fully vaccinated (at least two weeks after their last dose of COVID-19 vaccine), even in a low vaccination, high case setting, is not required to quarantine if exposed to a case. In the school setting, fully vaccinated individuals who are exposed to COVID-19 during a higher risk exposure should monitor for symptoms and seek testing if symptoms develop.  
  • School-Level Vaccination Rate
    • If at least 80% of individuals age 12 and older within a school community have received at least one dose of COVID-19 vaccine, no one, including unvaccinated individuals, needs to quarantine following a typical classroom exposure to a case.  
  • Weekly Serial Testing
    • Schools can also implement weekly serial testing in their schools. Additionally, students of all ages who are actively participating in at least weekly serial testing should not be required to quarantine following typical classroom exposures to a positive case of COVID-19. School districts may opt into a free and voluntary statewide serial testing program. If a school or school district is interested in enrolling in this program, please contact
    • If schools have at least 70% of their unvaccinated students and staff actively participating in serial testing, students and staff should not be required to quarantine following a typical classroom exposure to a case of COVID-19. 
  • Masking
    • CDPHE recommends that unvaccinated students not be required to quarantine following a typical classroom exposure  if both the infected individual and the exposed student(s) were wearing well-fitting masks correctly and consistently over the mouth and nose during the exposure.
    • In classroom settings, CDPHE recommends quarantine for unvaccinated close contacts that were within six feet for 15 minutes or more of an infected individual if either the infected individual or the contact were unmasked during the exposure. Note that this guidance differs slightly from current CDC guidance.  CDC’s definition of a close contact and need for quarantine in a typical classroom only excludes students who were within three to six feet of an infected individual if both parties were wearing masks. CDPHE does not specify a minimum of three feet when excluding exposed students from quarantine, if both the infected individual and the exposed student(s) were wearing masks and no direct physical contact occurred. CDPHE’s “Who Needs to Quarantine?” tool is updated to provide additional clarification.  
Higher risk exposures

Several close contact situations would be considered higher risk exposures to COVID-19.  The state recommends local public health take a heightened risk approach to these higher risk exposures, which should include quarantine of unvaccinated, exposed individuals. These exposures are significantly higher risk than typical activities within a classroom. Examples include: 

  • Indoor or high contact athletic competitions.
  • Evaluating or assessing ill students or staff.
  • Performing an aerosol-generating procedure.
  • Caring for a young child (feeding, holding, or diapering).
  • Interactions between young children where it is not age appropriate to remain seated or physically distanced. 
  • Indoor forced exhalation activities such as singing, exercising, or playing a wind or brass instrument. 

This is not an exhaustive list, and public health authorities can assist with determining whether or not quarantine is necessary after a particular exposure. Schools should discuss these more complex cases with their local public health agency.

Staff and students who are exposed to a case of COVID-19 outside of the school classroom, including social settings, athletics, workplaces, and household exposures, will likely be required to quarantine, pursuant to statutory and regulatory public health authority. Students participating in high-risk activities (such as unmasked indoor athletic competitions) and individuals who are at higher risk for severe infection will be strongly encouraged to get vaccinated for their own protection. 

Individuals at higher risk for severe disease

Individuals should discuss their personal risk factors with their health care providers. Individuals determined to be at higher risk for severe disease should get vaccinated as soon as they are eligible in consultation with their health care provider. If these individuals are not eligible for vaccination, or vaccination is not medically advised, serial testing and masking indoors is strongly recommended. Schools may consider universal masking requirements, ventilation improvements, and other protective measures when they serve or employ large numbers of high-risk or vulnerable individuals. 

Positive cases and outbreaks

As described above, all positive cases will be required to isolate and stay home to protect others, pursuant to statutory and regulatory public health authority. Once a school has an outbreak that impacts multiple classrooms, school leadership should work with their local public health authority to determine what additional mitigation strategies may be necessary. Additional mitigation strategies may include: universal masking indoors, distancing, testing and contact tracing, and quarantine of close contacts.

Caveat: Variants of Concern circulating in communities could impact population-based strategies. 

Variants of COVID-19

CDC and CDPHE are actively monitoring the impact that variants of the COVID-19 virus may have on communities and individuals. The state is closely evaluating  variants that may cause more severe disease, could be more contagious, or may have a greater potential to infect those who are vaccinated or who have recently been infected with COVID-19. 

All variants of COVID-19 spread through exhaled viral particles generated by sick people, and the same protective measures that have helped keep students safe in schools throughout the past year will continue to be effective. These key strategies also help protect students and staff from other diseases, such as influenza and RSV, and include: 

  • Getting a vaccine as soon as possible.
  • Encouraging students and staff to stay home when sick or potentially contagious.
  • Universal masking indoors.
  • Improving indoor ventilation.
  • Practicing good hand and respiratory hygiene.
  • Appropriate cleaning of shared spaces and objects. 

More information about COVID-19 variants is available from CDC.


Encouraging vaccinations in schools

Vaccines are our best defense against COVID-19. Schools are encouraged to educate their communities about the safety and efficacy of COVID-19 vaccines and why they are so important for us to return to the Colorado we love. 

Resources for schools to educate their communities about the COVID-19 vaccine

CDPHE has developed many vaccination resources  to support this effort and added information about COVID-19 vaccines to our online vaccine education module

CDPHE is prepared to support schools who wish to host a vaccination event for their students, faculty, and staff. For more information or to request event support, see the Event Based Vaccination Request Form

Additional resource are available, including testimonials, talking points, social media graphics, and more, to help schools communicate effectively with their communities about the safety and effectiveness of the COVID-19 vaccines: 

The CDC and the American Academy of Pediatrics (AAP) have additional resources about the COVID-19 vaccines: 

Verifying vaccination status 

Schools can verify the vaccination status of their students using the Colorado Immunization Information System (CIIS) without written consent. Per FERPA, written consent must be obtained if a school wants to enter vaccination data for a student into CIIS. Statute does not permit schools to use CIIS to verify the vaccination status of employees or staff.

Acceptable proof of COVID-19 vaccination

Acceptable proof of COVID-19 vaccination will be the same as all other school-required vaccines. A student may provide the vaccination card that includes the name of the provider, name of the patient, date, type of vaccine, and lot number. For students who received their vaccine in Colorado, the school may verify proof of vaccination with CIIS. Schools do not need written consent to look up vaccination records in CIIS. Students who receive their vaccination outside of Colorado may provide both their vaccination cards and/or IIS records from the state where they received their shots.

Additionally, CDPHE has added COVID-19 vaccines to the “recommended vaccines” section of the official Colorado Certificate of Immunization to better enable incoming students to share records of their immunizations with their school. 



Per 6 CCR 1009-1 and Public Health Order 20-33, clinical labs and/or health care providers are required to report all COVID-19 test results, both positive and negative, to public health. If school personnel perform and interpret rapid testing on-site, they are functioning as a clinical lab and are required to report all results. Per 6 CCR 1009-1, schools and child care facilities are also required to report single cases of which they become aware to public health, even if testing was performed elsewhere. Schools are able to disclose this information to public health without prior written consent under FERPA’s health or safety emergency exception, because a person with COVID-19 represents a potential threat to the health and safety of others at the school. This is true even if there is not an outbreak.

Public health then interviews the people who have COVID-19 and conducts contact tracing to determine who might be close contacts of the case, and makes recommendations about isolation and quarantine.  

Schools and child care providers are required to report all outbreaks to their local public health agency or CDPHE within four hours per 6 CCR 1009-1.

Schools and child care providers must report both suspected and confirmed outbreaks.

Schools and child care providers can report outbreaks by:

  • Fill out the CDPHE COVID-19 outbreak report form and send it to the local public health agency (go here or email the PDF form).
  • Calling their local public health agency.
  • Calling CDPHE at 303-692-2700.


Other respiratory infections

COVID-19 spreads via the same mechanisms as influenza, RSV, and other important respiratory illnesses. Therefore, the same strategies that schools have used to protect students and staff from COVID-19 also slow the spread of these other diseases. These include:

  • Getting a vaccine as soon as possible.
  • Encouraging students and staff to stay home when sick or potentially contagious.
  • Improving indoor ventilation through increased air exchanges and filtration.
  • Wearing a mask indoors.
  • Practicing good hand and respiratory hygiene.
  • Cleaning shared spaces and objects appropriately. 

Additionally, these diseases share many symptoms and it is not always possible to distinguish these illnesses from one another based on symptoms alone, even for experienced medical providers. Therefore, testing is important for anyone with symptoms of a respiratory infection to help guide an appropriate disease response. 


Consideration for travel and school breaks

Travel may put individuals at increased risk of contracting COVID-19, especially those that are not fully vaccinated. Travel may involve crowded public vehicles and spaces, where close contact with a high number of unique contacts with unknown vaccination status may occur.

The same layered mitigation strategies used in schools are recommended when traveling, especially those who are not yet fully vaccinated. Masking is recommended for anyone two years old and older in crowded indoor spaces, and is required on public transportation and in transportation hubs by federal order.

Families and staff should be encouraged to get vaccinated before traveling and to use layered mitigation strategies to stay safe. After returning, students and staff should monitor for symptoms and get tested if symptoms develop. 


For more information or questions regarding school guidance,
please contact or scan the QR code below.

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