Contact Tracing

In public health, contact tracing is the process of identification of persons who may have come into contact with an infected person ("contacts") by tracing and quarantining the close contacts of infected individuals, testing them for infection, public health aims to reduce infections in the population. Diseases for which contact tracing is commonly performed include tuberculosis, vaccine-preventable infections like measles, sexually transmitted infections (including HIV), blood-borne infections, ebola, some serious bacterial infections, and novel infections (e.g. SARS-CoV, H1N1, and COVID-19). The goals of contact tracing are:

  • To interrupt ongoing transmission and reduce the spread of an infection
  • To alert contacts to the possibility of infection and offer preventive services or prophylactic care
  • To offer diagnosis, counseling and treatment to already infected individuals
  • If the infection is treatable, to help prevent reinfection of the originally infected patient
  • To learn about the epidemiology of a disease in a particular population
  • To offer community resources to cases and close contacts 

Contact tracing has been a pillar of communicable disease control in public health for decades. The eradication of smallpox, for example, was achieved not by universal immunization, but by exhaustive contact tracing to find all infected persons. This was followed by isolation of infected individuals and immunization of the surrounding community and contacts at-risk of contracting smallpox.

In cases of diseases of uncertain infectious potential, contact tracing is also sometimes performed to learn about disease characteristics, including infectiousness.

In the case of a highly infectious disease such as COVID-19, contact tracers need to quickly locate and talk with the case, assist in arranging for infectious individuals to isolate themselves, and work with the case to identify people with whom they have been in close contact. Time is of the essence in contacting close contacts and arranging for isolation and self-quarantine in order to prevent further spread of COVID-19. If you receive a call from the Summit County Contact Tracing team, please respond immediately.


Contact Tracing WorkflowContact Tracing Workflow

What questions do COVID-19 contact tracers ask?

Here are some sample questions that contact tracers will ask in order to complete a case investigation 

  • How have you been feeling? When did your symptoms start and what symptoms did you have?
  • Where do you work (name, location(s), hours)?
  • What department do you work in, what do you do for lunch break, do you have contact with others outside of your department, do you have contact with the public? 
  • Do you have a second job or volunteer?
  • Tell me about your home, who lives with you? 
  • Do you have a bedroom and bathroom to be able to isolate from your household contacts?
  • Do you need assistance with meal delivery, financial assistance, or other community resources?

What is a Close Contact?

For COVID-19, a close contact is defined as any individual who was within 6 feet of an infected person for at least 15 minutes starting from 2 days before illness onset (or, for asymptomatic patients, 2 days prior to positive specimen collection) until the time the patient is isolated.

What is a close contact diagram

What is a Confirmed Positive Case?

Cases are considered confirmed when there has been a positive molecular amplification test (such as PCR) performed by a lab.

What is a Probable Case?

A person meeting clinical criteria AND epidemiologic evidence with no confirmatory laboratory testing performed for COVID-19; A person meeting presumptive laboratory evidence AND either clinical criteria OR epidemiologic evidence; A person meeting vital records criteria with no confirmatory laboratory testing performed for COVID-19.

Isolation and Quarantine

Isolation and quarantine help protect the public by preventing exposure to people who are sick or have been exposed to people who are sick. Generally, as long as the site is suitable, a person’s residence is the preferred setting for quarantine and isolation, according to the CDC. For more information on isolation and quarantine, visit the Colorado Department of Public Health and Environment.

Isolation is used to separate people infected with the virus (those who are sick with COVID-19 and those with no symptoms) from people who are not infected. People who are in isolation should stay home until it’s safe for them to be around others. In the home, anyone sick or infected should separate themselves from others by staying in a specific “sick room” or area and using a separate bathroom (if available).

Quarantine keeps someone who might have been exposed to the virus away from others.

When to Isolate?

Persons must Isolate for any of the following reasons:

  1. Person has a positive COVID-19 test, or
  2. Person has one of the following symptoms AND no alternative more likely diagnosis: fever (>100.4°F) or chills, cough, shortness of breath or difficulty breathing, fatigue, muscle or body aches, headache, new loss of taste or smell, sore throat, congestion or runny nose, nausea, vomiting or diarrhea. This list does not include all possible symptoms. CDC will continue to update this list as we learn more about COVID-19.
  3. Person has one of the symptoms listed in item #2 above and has had close contact with someone who tested positive for COVID-19.

How long must a person Isolate?

A person who meets the exclusion criteria described above must Isolate until:

  • Person has no fever for at least 24 hours (without using medicine that reduces fevers), AND
  • Other symptoms have improved, AND
  • At least 10 days have passed since your symptoms first appeared.

When to Quarantine?

Person has had close contact with someone who tested positive for COVID-19.

How long must a person Quarantine?

A person who has had close contact with someone diagnosed with COVID-19 must quarantine for 14 days from the last contact. 

Additional Resources

For further information on Isolation, Quarantine, and Testing, refer to our Guidance for Sick Individuals.

More information on How to Protect Yourself and Others from COVID-19.

Summit County COVID-19 Case Data