316704A May 27, 2020 3:25 PM

cdc.gov/coronavirus

This web page highlights basic principles of case investigation

and contact tracing to stop COVID-19 transmission; detailed 

guidance for health departments is available.

Case investigation and contact tracing, a core disease control measure 

employed by local and state health department personnel for decades, is a 

key strategy for preventing further spread of COVID-19. Immediate action is 

needed. Communities must scale up and train a large workforce and work 

collaboratively across public and private agencies to stop the transmission 

of COVID-19.

Certain core principles of case investigation and contact tracing 

must always be adhered to:

• Case investigation is part of the process of supporting patients with suspected or 

 confirmed infection.

• In case investigation, public health staff work with a patient to help them recall 

 everyone with whom they have had close contact during the timeframe while 

 they may have been infectious.

• Public health staff then begin contract tracing by warning these exposed 

 individuals (contacts) of their potential exposure as rapidly and sensitively 

 as possible.

• To protect patient privacy, contacts are only informed that they may have been 

 exposed to a patient with the infection. They are not told the identity of the patient 

 who may have exposed them.

• Contacts are provided with education, information, and support to understand 

 their risk, what they should do to separate themselves from others who are not 

 exposed, monitor themselves for illness, and the possibility that they could spread 

 the infection to others even if they themselves do not feel ill.

• Contacts are encouraged to stay home and maintain social distance from others 

 (at least 6 feet) until 14 days after their last exposure, in case they also become ill. 

 They should monitor themselves by checking their temperature twice daily and 

 watching for cough or shortness of breath. To the extent possible, public health 

 staff should check in with contacts to make sure they are self-monitoring and 

 have not developed symptoms. Contacts who develop symptoms should promptly 

 isolate themselves and notify public health staff. They should be promptly 

 evaluated for infection and for the need for medical care.

Case investigation and contact tracing is a specialized skill.

To be done effectively, it requires people with the training, supervision, and access to social 

and medical support for patients and contacts. Requisite knowledge and skills for case 

investigators and contact tracers include:

• An understanding of patient confidentiality, including the ability to conduct 

 interviews without violating confidentiality (e.g., to those who might overhear 

 their conversations)

• Understanding of the medical terms and principles of exposure, infection, 

 infectious period, potentially infectious interactions, symptoms of disease, 

 pre-symptomatic and asymptomatic infection

• Excellent and sensitive interpersonal, cultural sensitivity, and interviewing skills 

 such that they can build and maintain trust with patients and contacts

• Basic skills of crisis counseling, and the ability to confidently refer patients and 

 contacts for further care if needed

• Resourcefulness in locating patients and contacts who may be difficult to reach or 

 reluctant to engage in conversation

• Understanding of when to refer individuals or situations to medical, social, or 

 supervisory resources 

• Cultural competency appropriate to the local community

COVID-19

CASE INVESTIGATION AND CONTACT TRACING

Part of a Multipronged Approach to Fight the COVID-19 Pandemic 

COVID-19 Case Investigation and Contact Tracing for Health Departments
Case investigators and contact tracing is part of the process of 

supporting patients and warning contacts of exposure in order 

to stop chains of transmission. 

Given the magnitude of COVID-19 cases and plans to eventually relax mitigation efforts 

such as stay at home orders and social distancing, communities need a large number of 

trained case investigators and contact tracers. Case investigators need to quickly locate 

and talk with the patients, assist in arranging for patients to isolate themselves, and work 

with patients to identify people with whom the patients have been in close contact so 

the contact tracer can locate them. The actual number of staff needed is large and varies 

depending on a number of factors including but not limited to:

• The daily number of cases

• The number of contacts identified

• How quickly patients are isolated, and contacts are notified and advised to stay 

 home, self-monitor, and maintain social distance from others 

The time to start 

 building the trained 

 workforce is now.

Time is of the essence.

Identifying contacts and ensuring they do not interact with others is critical to protect 

communities from further spread. If communities are unable to effectively isolate patients 

and ensure contacts can separate themselves from others, rapid community spread of 

COVID-19 is likely to increase to the point that strict mitigation strategies will again be 

needed to contain the virus. 

Case investigators and contact tracers need to:

• Immediately identify and interview people with SARS CoV-2 infections and 

 COVID-19 (i.e., disease)

• Support isolation of those who are infected

• Warn contacts of their exposure, assess their symptoms and risk, and provide 

 instructions for next steps

• Link those with symptoms to testing and care 

Based on our current knowledge, a close contact is someone who was within 6 feet 

of an infected person for at least 15 minutes starting from 48 hours before illness 

onset until the time the patient is isolated. They should stay home, maintain social 

distancing, and self-monitor until 14 days from the last date of exposure. 

Case investigation and contact tracing in care facilities, other 

congregate living settings and households with many people 

living in one house is a priority. 

Case investigation and contact tracing of patients with COVID-19 potentially exposed at 

work and patients in healthcare facilities, congregate living settings or housing with many 

people is complex. Appropriate engagement with infection control and occupational 

health programs is recommended. Priority settings include: 

• Healthcare facilities including long-term care facilities

• Group home/board

• Homeless shelters

• Federal, state and local correctional facilities

• Crowded, multigenerational housing

In addition to healthcare workers, it is important to assess interactions between residents 

and all staff, including but not limited to activity coordinators, food service staff, and 

sanitation management. Transitional case management plans should be put in place for 

patients in isolation and contacts who are separated for monitoring. Management plans 

should also be created for transitioning from one setting to another, such as transitions 

from hospitals to acute or long-term care facilities or home isolation, or from prison and 

jail to parole and probation.

CASE INVESTIGATION and CONTACT TRACING Part of a Multipronged Approach to Fight the COVID-19 Pandemic 

COVID-19 Contact Tracing for Health Departments
Social services and housing will be needed for contacts unable to 

separate themselves from others in their current living situation. 

Separating contacts from people who are not exposed is critical to the success of any 

contact tracing effort and requires social supports for individual compliance and medical 

monitoring. First and foremost is the assessment of an individual’s ability to stay home 

and maintain social distance from others, a safe environment that provides the necessary 

supports (private room and bathroom, adequate food and water, and access to medication) 

and the ability to practice adequate infection control. For a portion of the U.S. population 

this will be a challenge, particularly for some of the most vulnerable populations. 

Support services for consideration include housing, food, medicine, and economic 

supports. For contacts without a primary care provider, linkage to clinical care may 

be needed. Support for medical monitoring includes patient care packages (e.g., 

thermometers, sanitizers, mask, gloves) and technological supports for medical 

monitoring (e.g., mobile phone apps). If possible, contacts should be asked to voluntarily 

stay home, monitor themselves, and maintain social distancing from others. However, 

health departments have the authority to issue legal orders of quarantine, should the 

situation warrant that measure.

Communication with the public is crucial. 

Engagement of the public with case investigators and 

contact tracers must be widely accepted in order to 

protect friends, family, and community members from 

future potential infections. Key public officials and community 

leaders will need to be engaged and supportive of case investigation 

and contact tracing efforts. Consider reaching out to community leaders as part of the 

neighborhood-level case investigation and contact tracing team. To be successful, a 

community will need public awareness, and understanding and acceptance of case 

investigation and contact tracing and the need for contacts to separate themselves from 

others who are not exposed. Community members need to take responsibility to follow 

the guidance from public health agencies.

Data management and technology will be needed. 

Case investigation, contact tracing, and contact follow-up and monitoring will need to 

be linked with timely testing, clinical services, and agile data management systems to 

facilitate real-time electronic transmission of laboratory and case data for public health 

action. Technology partners are key in the modification of existing systems and the 

development of new user-friendly data interfaces to manage multiple data streams with 

seamless interoperability. Case management tools can help automate key pieces of the 

case investigation and contact tracing process, making the overall process more efficient. 

Ideally, data systems would also include automated reports to aid in monitoring progress 

and outcomes of case investigation and contact tracing. Data sharing agreements between 

local, tribal and state, and federal jurisdictions need to be established or augmented to 

ensure timely and accurate data collection and sharing. 

The adoption of emerging technologies that can assist private and public health 

practitioners with client communication, medical monitoring, and strategies to 

amplify case investigation and contact tracing may greatly help with scaling up these 

acyivities as needed. Digital Contact Tracing Tools for COVID-19

Ongoing monitoring and assessment of case investigation and 

contact tracing efforts will be needed. 

Public health agencies and their partners will need to monitor some key components of 

their programs to improve performance as needed. Potential metrics routinely reviewed 

could include the following process and outcome measures: 

• Case interviewing: Time to interview from symptom onset and from diagnosis; 

 proportion interviewed; median number of contacts elicited; proportion with no 

 contacts elicited.

• Contact notification: Proportion of contacts notified; time from first potential 

 exposure to notification.

• Contact follow-up: Daily proportion of contacts whose status is evaluated; 

 proportion of contacts with symptoms evaluated within 24 hours of onset of 

 symptoms; proportion of contacts who complete their full self-monitoring period 

• Contact tracing efficacy: Percent of new COVID-19 cases arising among contacts 

 during self-monitoring period.

CASE INVESTIGATION and CONTACT TRACING Part of a Multipronged Approach to Fight the COVID-19 Pandemic 

COVID-19 Contact Tracing for Health Departments