Important update: Healthcare facilities
CDC has updated select ways to operate healthcare systems effectively in response to COVID-19 vaccination. Learn more
UPDATE
Given new evidence on the B.1.617.2 (Delta) variant, CDC has updated the guidance for fully vaccinated people. CDC recommends universal indoor masking for all teachers, staff, students, and visitors to K-12 schools, regardless of vaccination status. Children should return to full-time in-person learning in the fall with layered prevention strategies in place.
UPDATE
The White House announced that vaccines will be required for international travelers coming into the United States, with an effective date of November 8, 2021. For purposes of entry into the United States, vaccines accepted will include FDA approved or authorized and WHO Emergency Use Listing vaccines. More information is available here.
UPDATE
Travel requirements to enter the United States are changing, starting November 8, 2021. More information is available here.

Contact Tracing for COVID-19

Contact Tracing for COVID-19
Updated Feb. 10, 2022

CDC is reviewing this page to align with updated guidance.

Summary of Recent Changes

  • Changes made to reflect updated guidance for isolation and quarantine.

View Previous Updates

The public health evaluation of close contacts to patients with laboratory-confirmed or probable COVID-19 may vary depending on the exposure setting. Contacts in special populations and/or congregate settings require additional considerations and may need handoff to a senior health department investigator or special team. Additional guidance on managing these contacts can be found in Outbreak Investigations.

Close contact evaluation and monitoring priorities

In jurisdictions with testing capacity, symptomatic and asymptomatic close contacts to patients with confirmed and probable COVID-19 should be evaluated and monitored. For areas with insufficient testing support and/or limited public health resources, the following evaluation and monitoring hierarchy (Box 4) and the case investigation and contact tracing prioritization recommendations can be used to help guide prioritization. The hierarchy is based on the assumption that if close contacts listed in Priority 1 become infected, they could potentially expose many people, those at higher risk for severe disease, or critical infrastructure workers. If close contacts in Priority 2 become infected, they may be at higher risk for severe disease, so prompt notification, monitoring, and linkage to needed medical and support services is important.

When prioritizing close contacts to evaluate and monitor, jurisdictions should be guided by the local characteristics of disease transmission, demographics, and public health and healthcare system capacity. Some states require mandatory testing for specific circumstances. Local decisions depend on local guidance and circumstances.

Box 4. Close contact evaluation and monitoring hierarchy

The case investigation and contact tracing prioritization recommendations are intended to provide additional information and an overview of prioritization strategies for consideration. Implementation should be guided by what is feasible, practical, and acceptable, as well as tailored to the needs of each community.

EVALUATE/MONITOR CLOSE CONTACTS WHO ARE:

PRIORITY 1

  • Hospitalized patients
  • Healthcare personnel (HCP)
  • First responders (e.g., EMS, law enforcement, firefighters)
  • Individuals living, working or visiting acute care, skilled nursing, mental health, and long-term care facilities
  • Individuals living, working or visiting community congregate settings (e.g., correctional facilities, homeless shelters, educational institutions, mass gatherings, and workplaces including production plants)
  • Member of a large household living in close quarters
  • Individuals who live in households with a higher risk individual or who provide care in a household with a higher risk individual (Note: Household members who likely had extensive contact with a patient with COVID-19 should constitute the highest risk close contacts.)

PRIORITY 2

PRIORITY 3

  • Individuals with symptoms who do not meet any of the above categories

PRIORITY 4

  • Individuals without symptoms who do not meet any of the above categories

*Consider moving to Priority 1 any critical infrastructure worker who works closely with other critical infrastructure workers and/or is in close contact with large numbers of people (e.g., transportation, food service).

Note: Boxes 1-3 can be found under the “Investigating a COVID-19 Case” section of the guidance.

Contact tracers use clear protocols to notify, interview, and advise close contacts to patients with confirmed or probable COVID-19. Jurisdictions can use the following steps and considerations as a framework when developing a protocol for the tracing of close contacts.

Contact tracing workflow: accessible version available at https://www.cdc.gov/coronavirus/2019-ncov/php/contact-tracing/contact-tracing-plan/contact-tracing.html

COVID-19 Contact Tracing Workflow

Step 1: Rapid notification of exposure

For contacts in your health department’s jurisdiction:

  • A close contact to a patient with confirmed or probable COVID-19 should be notified of their exposure as soon as possible (within 24 hours of contact elicitation). The patient may elect to notify some or all of their close contacts before the contact tracer.
  • The identity of the patient or other identifying information will not be revealed, alluded to, or confirmed by the contact tracer, even if explicitly asked by a contact.
  • Contacts can be notified through different channels such as phone, text, email, or in-person (if appropriate) in the primary language of the individual. Special consideration should be given to ensure culturally and linguistically appropriate communications, if possible. The protocol should clearly outline the primary and secondary means of notifying a contact.
  • Protocols should be in place to provide services to people who are deaf or who have hearing loss.
  • Depending on the information elicited during the case investigation, locating information for the contact may be insufficient. Tips on additional resources that may be used to obtain missing locating information can be found in Appendix B. Every effort should be made to reach the contact remotely before attempting in-person communication.

Operational Questions to Consider

  • Who will conduct contact notification in your jurisdiction? (e.g., case investigators, other public health staff, volunteers, contracted staff)
  • How will you collaborate to transfer contact information from one jurisdiction to another to ensure notification of exposure for contacts outside of your jurisdiction?
  • How can your jurisdiction incorporate existing or new technology (e.g., mobile app) into a contact tracer’s workflow to speed up contact notification?
  • When is in-person notification needed? Contact tracers expected to perform in-person notification need appropriate training on infection prevention and control practices and must obtain any necessary PPE prior to conducting in-person activities.
  • Will contact tracers be asked to notify a client’s household contacts/known contacts, or will the client be asked to make these notifications?
  • How will notification of exposure be handled for minors?
  • If an entire household is exposed, will there be one point of contact for the household or separate contacts for every household member?
  • How will a contact tracer follow up with a contact if the client makes the notification?
  • How will you work with employers when many contacts are within a work setting?

Step 2: Contact interview

  • Every effort should be made to interview the close contact by telephone, text, or video conference instead of in-person. The interview should be conducted in the individual’s primary language (through interpretation services, if necessary). For in-person interviews, guidance on recommended infection prevention and control practices at a home or non-home residential setting can be found on CDC’s Evaluating PUIs Residential page.
  • Appendix C includes critical data elements that can be incorporated into a jurisdiction’s form used to interview contacts to assess symptoms, better characterize their underlying risk for infection, and assess home and social factors that could impact compliance with self-quarantine.
  • Notification of Exposure – A Contact Tracer’s Guide for COVID-19 focuses on communication strategies for contact interviews and provides suggested language for each topic area covered in an interview.

Operational Questions to Consider

  • If a contact needs to be interviewed via an interpreter, how will those services be accessed?
  • How will your jurisdiction navigate confidentiality challenges when the calendar date of an exposure easily reveals who may have exposed a contact to COVID-19?
  • What steps will be taken if a contact is unwilling or unable to be interviewed or cannot be located?

Step 2a: Recommendations for close contacts

People who are identified as close contacts should follow CDC guidelines to protect themselves and others. Recommendations for close contacts to quarantine, get tested, and wear well-fitting masks after exposure to people diagnosed with COVID-19 will vary depending on their up to date vaccination status and history of prior COVID-19 diagnosis within the past 90 days. People who have come into close contact with persons diagnosed with COVID-19 should follow the recommendations outlined on the COVID-19 Quarantine and Isolation web page.

All close contacts should monitor for COVID-19 symptoms and promptly get tested and isolate away from others if they develop symptoms. People with symptoms of COVID-19 should seek emergency medical care immediately if they develop emergency warning signs.

Operational Questions to Consider

  • Under what circumstances will quarantine be mandatory (under public health orders) as opposed to voluntary?
  • Who will be referred for testing (e.g., symptomatic, asymptomatic) and how (e.g., testing site, home test kit)?
  • How will contacts be checked against databases of already confirmed cases to ensure they are not already in self-isolation?
  • Will contact tracers be collecting diagnostic respiratory specimens?
  • How will contacts be monitored for self-quarantine compliance?
  • What services are available in the community to support workers who need to stay home and self-quarantine?
  • How can your jurisdiction incorporate technology, such as a mobile app or online tool, to assist with active monitoring of close contacts (e.g., symptom reporting, temperature checks)?
  • Can your jurisdiction supply a letter/email to close contacts documenting their need to self-quarantine for a specified date range? Contacts could provide this to their employers to verify the reason for a work absence.

Step 2b: Assessing quarantine support needs

Emphasis should be placed on helping close contacts identify any need for social support during quarantine.

Quarantine of close contacts exposed to COVID-19 prevents transmission to others and is critical to the success of case investigation and contact tracing efforts. For most, quarantine can take place at home. If possible, close contacts should be asked to voluntarily stay home, monitor themselves, and maintain social distance from others. Recommendations for close contacts vary based on their up to date vaccination status or history of prior infection in the past 90 days. Close contacts who are required to quarantine should follow the recommendations outlined on the COVID-19 Quarantine and Isolation webpage. Adherence to quarantine instructions may depend on the support provided to close contacts.

Quarantine requires that a close contact remain in a specific room separate from other non-exposed people and pets in the home, and ideally with access to a separate bathroom. The contact tracer should assess an individual’s ability to quarantine in a safe environment that provides access to a private room and bathroom, as well as access to adequate food and water among other considerations.

For a portion of the U.S. population, having a safe environment with a private room and bathroom, and adequate food and water will be a challenge. Considerations must also be made for close contacts who express fear of abuse or violence if they must quarantine at home. Additionally, some close contacts (e.g., single parents, nursing mothers, parents with children and toddlers, and other primary caregivers) may face other challenges, such as having to provide child care or dependent adult care, that may affect their ability to quarantine. Social services, housing, and other supportive services will be needed for those contacts who are unable to separate themselves from others in their current living situation. See Support Services for further considerations.

Close contacts will also need to be supported with health coaching to ensure that each day they monitor their temperature and the onset of any COVID-19 symptoms and have access to clinical services should symptoms appear. Coordination of access to telehealth services may be needed for contacts without virtual access to a primary care provider. If possible, close contacts in need of additional support should be provided a COVID-19 kit with the following resources during quarantine*:

  • Washable cloth face covering
  • Gloves
  • Digital thermometer
  • Alcohol-based hand sanitizer and soap
  • COVID-19 health education materials (translated into the appropriate language)
  • EPA-registered household disinfectant and instructions for cleaning and disinfecting your home for those sharing space with others
  • A hotline/warmline to address any support needs during the quarantine period, including medical support

*The composition of the COVID-19 kit will depend on the jurisdiction’s resources.

Operational Questions to Consider

  • Are there other resources that your jurisdiction can share to provide health advice and answer questions? (e.g., mobile app, hotline/call center, CDC Coronavirus Symptom Self-Checker, CDC-INFO)

Step 3: Medical monitoring

  • Contacts who agree to self-quarantine will ideally receive active daily monitoring through real-time communication methods (e.g., telephone calls, video conferencing) to check-in on their temperature and COVID-19 symptoms throughout the length of their self-quarantine.
  • If a jurisdiction’s resources do not allow for active daily monitoring, contacts will be asked to self-monitor and communicate remotely (e.g., email, recorded video, telephone message, text, monitoring apps) to notify public health authorities of their health status and promptly communicate any new symptoms or symptoms of increasing severity. A daily temperature/symptom log [215 KB, 2 Pages] can be provided to the contact electronically to aid in self-monitoring.
  • For those individuals self-monitoring and sharing reports remotely, reports must be received by the agreed upon time each day, and protocol must address follow-up actions for contacts who do not report out.
  • Contacts who develop and report symptoms should be linked to clinical care and testing. For contacts who report testing, follow up to confirm results.
    • If positive, the contact will be referred to a case investigator.
    • If negative, symptomatic contacts should continue to self-quarantine and follow all recommendations of public health authorities. A second test and additional medical consultation may be needed if symptoms do not improve.
    • If testing is not available, symptomatic close contacts should be advised to self-isolate and be managed as a probable case. Self-isolation is recommended for people with probable or confirmed COVID-19 who have mild illness and are able to recover at home.

Operational Questions to Consider

  • What steps will be taken for contacts under self-monitoring who do not report as required? How intensive will the outreach be (e.g., same-day home visit)?

Step 3a: Monitoring and isolation instructions

  • Clients with probable or confirmed COVID-19 should be advised to self-isolate immediately, if they are not doing so already. Self-isolation is recommended for people with probable or confirmed COVID-19 who have mild illness and are able to recover at home.
  • It should be made clear to the client whether the isolation instructions are voluntary or mandatory, as determined by state or local public health authorities.
  • Advise clients to cancel or postpone plans that involve social gatherings, vacations or other planned travel until cleared for these activities by public health authorities (based on the guidance above).
    • Local and state health departments may request federal public health travel restrictions, which prevent listed travelers from boarding commercial airplanes and trigger public health notification if they enter the United States by land or sea, to support state- or local-mandated isolation for infected individuals.
    • ​Support with federal public health travel restrictions may be requested by public health partners by contacting the CDC quarantine station with jurisdiction for the area.
  • If needed, jurisdictions should refer clients for social support services (for example, food, childcare, housing, and other services) to help encourage clients to stay at home and comply with isolation.
  • If clients refuse to comply voluntarily with self-isolation instructions, jurisdictions should consider what options (e.g., legal order for isolation) are available to them under relevant state or local legal authority.
  • The client should be informed of COVID-19 symptoms to monitor for and be instructed to get medical attention immediately if he/she experiences any emergency warning signs, such as trouble breathing. Clients with no primary healthcare provider will need linkage to telemedicine or phone consultation.
  • The client should also be informed of ways to prevent infection among those living in their household.
  • Additional isolation guidance should be reviewed with the client and instructional materials provided. Sample materials can be found on the CDC website:
  • All instructions should be provided in a client’s primary language.

Operational Questions to Consider

  • Under what circumstances will isolation be mandatory (under public health orders) as opposed to voluntary? How will this distinction be made clear to a patient?
  • How will clients be monitored for isolation compliance?
  • In the event that self-isolation is not feasible, what alternative supports exist, and/or what risk-reduction measures can be taken?

Step 4: Contact close out​

  • The duration of quarantine will depend on whether the close contact develops symptoms. To determine the end of quarantine and the timing for contact close out refer to current CDC guidance for quarantine.
  • Close contacts who are symptomatic or test positive should begin isolation.
  • Close contacts should watch for symptoms and wear a well-fitting mask around other people for 10 days after their last close contact.

Operational Questions to Consider

  • Will the health department send an alert notification to the individual one day prior to the end of self-quarantine to double-check signs/symptoms and authorize return to work?
  • Will a “return to work” letter be available to contacts who request one after completing the monitoring period?
  • Will a warmline be offered to address any post-monitoring issues?

Previous Updates